### get_x_start()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1region.html

Getter for the region's start position.

```APIDOC
## get_x_start()

### Description
Gets the region start position.

### Returns
- **real** - The start position in x-direction.

```

--------------------------------

### get_sources()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Gets all sources of this scenario.

```APIDOC
## get_sources()

### Description
Gets all sources of this scenario.

### Method
const std::vector<std::shared_ptr<source> >& mbsolve::scenario::get_sources() const

### Parameters
None

### Returns
- **const std::vector<std::shared_ptr<source> >&** - All sources of this scenario.
```

--------------------------------

### get_records()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Gets all records of this scenario.

```APIDOC
## get_records() n
### Description
Gets all records of this scenario.

### Method
const std::vector<std::shared_ptr<record> >& mbsolve::scenario::get_records() const

### Parameters
None

### Returns
- **const std::vector<std::shared_ptr<record> >&** - All records of this scenario.
```

--------------------------------

### qm_superop::get_num_levels() const

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1qm__superop.html

Get the number of levels.

```APIDOC
## qm_superop::get_num_levels() const

### Description
Get the number of levels.

### Parameters
None.

### Return Value
- **unsigned int** - The number of levels.
```

--------------------------------

### const std::string& get_name() const

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1device.html

Gets the device name.

```APIDOC
## const std::string& get_name() const

### Description
Gets the device name.

### Returns
The device name as a string reference.

```

--------------------------------

### const std::set<std::string>& get_used_materials() const

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1device.html

Gets the IDs of used materials.

```APIDOC
## const std::set<std::string>& get_used_materials() const

### Description
Gets the IDs of used materials.

### Returns
A set of material IDs.

```

--------------------------------

### get_ic_density()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Gets initial conditions for density matrix.

```APIDOC
## get_ic_density()

### Description
Gets initial conditions for density matrix.

### Method
std::shared_ptr<ic_density> mbsolve::scenario::get_ic_density() const

### Parameters
None

### Returns
- **std::shared_ptr<ic_density>** - The initial conditions for density matrix.
```

--------------------------------

### real get_length() const

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1device.html

Gets the device length.

```APIDOC
## real get_length() const

### Description
Gets the device length.

### Returns
The device length as a real number.

```

--------------------------------

### material::get_qm

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1material.html

Gets a pointer to the quantum mechanical description. This is a const member function that returns a shared pointer to the qm_description object.

```APIDOC
## material::get_qm

### Description
Gets a pointer to the quantum mechanical description. This is a const member function that returns a shared pointer to the qm_description object.

### Method
Member Function

### Signature
`std::shared_ptr<qm_description> mbsolve::material::get_qm() const`

### Returns
- **std::shared_ptr<qm_description>** - Pointer to the quantum mechanical description.

### Example
```cpp
// Get the quantum mechanical description
auto qm = mat->get_qm();
```
```

--------------------------------

### const std::vector<std::shared_ptr<region>>& get_regions() const

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1device.html

Gets all regions of the device.

```APIDOC
## const std::vector<std::shared_ptr<region>>& get_regions() const

### Description
Gets all regions of the device.

### Returns
A vector of shared pointers to the regions.

```

--------------------------------

### Example Class Hierarchy for Graph Generation

Source: https://mriesch-tum.github.io/mbsolve/graph_legend.html

A set of C++ class definitions used to demonstrate various inheritance and containment relationships in Doxygen graphs.

```cpp
/*! Invisible class because of truncation */
class Invisible { };
/*! Truncated class, inheritance relation is hidden */
class Truncated : public Invisible { };
/* Class not documented with doxygen comments */
class Undocumented { };
/*! Class that is inherited using public inheritance */
class PublicBase : public Truncated { };
/*! A template class */
template<class T> class Templ { };
/*! Class that is inherited using protected inheritance */
class ProtectedBase { };
/*! Class that is inherited using private inheritance */
class PrivateBase { };
/*! Class that is used by the Inherited class */
class Used { };
/*! Super class that inherits a number of other classes */
class Inherited : public PublicBase,
protected ProtectedBase,
private PrivateBase,
public Undocumented,
public Templ<int>
{
private:
Used *m_usedClass;
};
```

--------------------------------

### initialize(real x)

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1ic__density.html

Pure virtual method that returns the initial density matrix for a given position x. This is the primary interface for subclasses to implement.

```APIDOC
## initialize(real x)

### Description
Returns the initial density matrix for a given position x. This is a pure virtual method that must be implemented by derived classes.

### Method
initialize

### Signature
virtual const qm_operator& initialize(real x) = 0

### Parameters
- **x** (real) - Required - The position for which the initial density matrix is returned.

### Returns
- **const qm_operator&** - The initial density matrix at position x.

### Implemented In
- mbsolve::ic_density_const
```

--------------------------------

### run()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1solver__cpu__fdtd__red.html

Executes the solver. This method is virtual and implements the pure virtual method from mbsolve::solver.

```APIDOC
## run()

### Description
Executes the solver. This method is virtual and implements the pure virtual method from mbsolve::solver.

### Signature
cpp
void run() const


### Parameters
- None

### Returns
- void

```

--------------------------------

### get_type()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1record.html

Gets type of the record.

```APIDOC
## mbsolve::record::get_type()

### Description
Gets type of the record.

### Returns
- **type** - Type of the record.

```

--------------------------------

### get_name()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1record.html

Gets name of the record.

```APIDOC
## mbsolve::record::get_name()

### Description
Gets name of the record.

### Returns
- **const std::string&** - Name of the record.

```

--------------------------------

### qm_description constructor

Source: https://mriesch-tum.github.io/mbsolve/qm__description_8hpp_source.html

Constructs a quantum mechanical description with carrier density, Hamiltonian, dipole operator, and relaxation superoperator.

```APIDOC
## qm_description constructor

### Description
Constructs a quantum mechanical description with carrier density, Hamiltonian, dipole operator, and relaxation superoperator.

### Method
Constructor

### Signature
`qm_description(real carrier_density, const qm_operator& hamiltonian, const qm_operator& dipole_operator, std::shared_ptr<qm_superop> relaxation_superop)`

### Parameters
- **carrier_density** (real) - Required - The density of charge carriers.
- **hamiltonian** (const qm_operator&) - Required - The Hamiltonian operator.
- **dipole_operator** (const qm_operator&) - Required - The dipole moment operator.
- **relaxation_superop** (std::shared_ptr<qm_superop>) - Required - The relaxation superoperator.

### Returns
No return value (constructor).
```

--------------------------------

### scenario::scenario (constructor 2)

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Constructs a scenario with a name, number of grid points, end time, and initial conditions for the density matrix.

```APIDOC
## scenario::scenario (constructor 2)

### Description
Constructs a scenario with the given name, number of spatial grid points, simulation end time, and initial conditions for the density matrix.

### Signature
mbsolve::scenario::scenario(const std::string & _name_, unsigned int _num_gridpoints_, real _endtime_, std::shared_ptr< ic_density > _density_init_)

### Parameters
- **name** (const std::string &) - [in] - Name of the scenario.
- **num_gridpoints** (unsigned int) - [in] - Number of spatial grid points.
- **endtime** (real) - [in] - Simulation end time.
- **density_init** (std::shared_ptr< ic_density >) - [in] - Initial conditions for density matrix.
```

--------------------------------

### get_timestep_size()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Gets time step size.

```APIDOC
## get_timestep_size() n
### Description
Gets time step size.

### Method
real mbsolve::scenario::get_timestep_size() const

### Parameters
None

### Returns
- **real** - The time step size.
```

--------------------------------

### scenario::scenario (constructor 1)

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Constructs a scenario with a name, number of grid points, end time, and an initial density matrix.

```APIDOC
## scenario::scenario (constructor 1)

### Description
Constructs a scenario with the given name, number of spatial grid points, simulation end time, and initial density matrix.

### Signature
mbsolve::scenario::scenario(const std::string & _name_, unsigned int _num_gridpoints_, real _endtime_, const qm_operator & _rho_init_)

### Parameters
- **name** (const std::string &) - [in] - Name of the scenario.
- **num_gridpoints** (unsigned int) - [in] - Number of spatial grid points.
- **endtime** (real) - [in] - Simulation end time.
- **rho_init** (const qm_operator &) - [in] - Initial density matrix.
```

--------------------------------

### get_num_timesteps()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Gets number of time steps.

```APIDOC
## get_num_timesteps() n
### Description
Gets number of time steps.

### Method
unsigned int mbsolve::scenario::get_num_timesteps() const

### Parameters
None

### Returns
- **unsigned int** - The number of time steps.
```

--------------------------------

### qm_desc_2lvl constructor

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1qm__desc__2lvl.html

Constructs a two-level system description with the given carrier density, transition frequency, dipole moment, scattering rate, dephasing rate, and equilibrium inversion.

```APIDOC
## Constructor: qm_desc_2lvl

### Description
Constructs a two-level system description with the Hamiltonian and the dipole moment operator.

### Signature
qm_desc_2lvl(real carrier_density, real transition_freq, real dipole_moment, real scattering_rate, real dephasing_rate, real equilibrium_inversion = -1.0)

### Parameters
- **carrier_density** (real) - Required - Density of particles in the system.
- **transition_freq** (real) - Required - Transition frequency between upper and lower laser level.
- **dipole_moment** (real) - Required - Dipole moment between upper and lower laser level.
- **scattering_rate** (real) - Required - Describes the decay of the population inversion towards equilibrium_inversion.
- **dephasing_rate** (real) - Required - Describes the decay of the coherence term.
- **equilibrium_inversion** (real) - Optional - Equilibrium value of the population inversion. Default is -1.0 (all particles in lower energy level).
```

--------------------------------

### get_gridpoint_size()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Gets grid point size.

```APIDOC
## get_gridpoint_size()

### Description
Gets grid point size.

### Method
real mbsolve::scenario::get_gridpoint_size() const

### Parameters
None

### Returns
- **real** - The grid point size.
```

--------------------------------

### Initialize Solver Constants

Source: https://mriesch-tum.github.io/mbsolve/algo__lindblad__cvr__rodr_8hpp_source.html

Initializes the simulation constants (sim_constants) based on the quantum mechanical description, including Hamiltonian contributions, dissipation terms, and equilibrium vectors.

```cpp
/* check whether number of levels matches solver */
if (qm->get_num_levels() != num_lvl) {
throw std::invalid_argument(
"Number of energy levels does not "
"match selected solver!");
}

/* create coherence vector representation */
cv_representation cvr(qm);

/* polarization constant */
sc.M_CP = 0.5 * qm->get_carrier_density();

/* time step size */
sc.d_t = time_step;

/* dissipation term in cvr */
real_matrix_t G = cvr.get_relaxation_superop();

/* time-independent Hamiltonian contribution in cvr */
real_matrix_t M_0 = cvr.get_hamiltonian();

/* time-independent part of the Lindblad equation rhs */
sc.M = M_0 + G;

/* dipole moment Liouvillian in cvr form (matrix) + squared */
sc.U = -cvr.get_dipole_operator();
sc.U2 = sc.U * sc.U;
sc.theta_1 = sqrt(
pow(sc.U(0, 1), 2) + pow(sc.U(0, 2), 2) + pow(sc.U(1, 2), 2));

/* time-independent propagator, half step */
sc.A1 = (sc.M * time_step / 2).exp();

/* prepare time-dependent propagator */
fill_coefficients(sc);

/* dipole moment operator in cvr form (vector) */
sc.v = cvr.get_dipole_operator_vec();

/* equilibrium terms */
sc.d_eq = cvr.get_equilibrium_vec();
real eps = std::numeric_limits<real>::epsilon();
if (sc.d_eq.isZero(eps)) {
sc.d_in = density::Zero();
} else {
/* solve equation system M * d_in = d_eq */
sc.d_in = sc.M.fullPivLu().solve(sc.d_eq);
real err = (sc.M * sc.d_in - sc.d_eq).norm() / sc.d_eq.norm();
if (err > 1e-3) {
throw std::invalid_argument("Time-indepent matrix not "
"invertible!");
}
}
```

--------------------------------

### get_endtime()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Gets the simulation end time.

```APIDOC
## get_endtime()

### Description
Gets the simulation end time.

### Method
real mbsolve::scenario::get_endtime() const

### Parameters
None

### Returns
- **real** - The simulation end time.
```

--------------------------------

### set_ic_density(std::shared_ptr<ic_density> _density_init_)

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Sets initial conditions for density matrix.

```APIDOC
## set_ic_density(std::shared_ptr<ic_density> _density_init_)

### Description
Sets initial conditions for density matrix.

### Method
set_ic_density

### Parameters
- **_density_init_** (std::shared_ptr<ic_density>) - Required - The initial density condition.

### Return Type
void
```

--------------------------------

### source::get_type

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1source.html

Gets the type of the source.

```APIDOC
## source::get_type

### Description
Gets the type of the source.

### Method
`type get_type() const`

### Returns
- **type** - The source type (hard_source or soft_source).

```

--------------------------------

### device(const std::string &name)

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1device.html

Constructs a device with the given name.

```APIDOC
## device(const std::string &name)

### Description
Constructs a device with the given name.

### Parameters
- **name** (const std::string&) - Required - Name of the device.

```

--------------------------------

### source::get_position

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1source.html

Gets the position of the source.

```APIDOC
## source::get_position

### Description
Gets the position of the source.

### Method
`real get_position() const`

### Returns
- **real** - The position of the source in meters.

```

--------------------------------

### result::get_rows

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1result.html

Gets the number of rows.

```APIDOC
## result::get_rows

### Description
Gets the number of rows.

### Signature
unsigned int get_rows() const

### Returns
- **unsigned int** - The number of rows.
```

--------------------------------

### Handle Non-Quantum Initialization

Source: https://mriesch-tum.github.io/mbsolve/algo__lindblad__cvr__rodr_8hpp_source.html

Resets simulation constants to zero when no quantum mechanical description is provided.

```cpp
} else {
/* no quantum mechanical description */
sc.has_qm = false;
sc.M_CP = 0.0;
sc.d_t = 0.0;
sc.M = real_matrix_t::Zero();
sc.U = real_matrix_t::Zero();
sc.U2 = real_matrix_t::Zero();
sc.theta_1 = 0.0;
sc.A1 = real_matrix_t::Zero();
sc.v = density::Zero();
sc.d_eq = density::Zero();
sc.d_in = density::Zero();

/* TODO initialize properly?:
real_matrix_t coeff_1[num_lvl/2];
real_matrix_t coeff_2[num_lvl/2];
real theta[num_lvl/2];
*/
}
```

--------------------------------

### qm_description::qm_description

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1qm__description.html

Constructor for the qm_description class, initializing the quantum mechanical description of an active region.

```APIDOC
## Constructor: qm_description

### Description
Constructs a quantum mechanical description of an active region with the given carrier density, Hamiltonian, dipole operator, and relaxation superoperator.

### Signature
```cpp
qm_description(real carrier_density, const qm_operator &hamiltonian, const qm_operator &dipole_operator, std::shared_ptr<qm_superop> relaxation_superop)
```

### Parameters
- **carrier_density** (real) - Required - Density of particles in the system.
- **hamiltonian** (const qm_operator&) - Required - Hamiltonian operator.
- **dipole_operator** (const qm_operator&) - Required - Dipole moment operator.
- **relaxation_superop** (std::shared_ptr<qm_superop>) - Required - Relaxation superoperator.

### Returns
No return value.
```

--------------------------------

### result::get_cols

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1result.html

Gets the number of columns.

```APIDOC
## result::get_cols

### Description
Gets the number of columns.

### Signature
unsigned int get_cols() const

### Returns
- **unsigned int** - The number of columns.
```

--------------------------------

### scenario::scenario (constructor with qm_operator)

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Constructs a scenario object with a name, number of grid points, end time, and an initial density operator.

```APIDOC
## scenario::scenario (constructor with qm_operator)

### Description
Constructs a scenario object with the given name, number of grid points, end time, and initial density operator.

### Signature
scenario(const std::string &name, unsigned int num_gridpoints, real endtime, const qm_operator &rho_init)

### Parameters
- **name** (const std::string&) - Required - The name of the scenario.
- **num_gridpoints** (unsigned int) - Required - The number of grid points.
- **endtime** (real) - Required - The end time of the simulation.
- **rho_init** (const qm_operator&) - Required - The initial density operator.
```

--------------------------------

### result::get_count

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1result.html

Gets the count of the result.

```APIDOC
## result::get_count

### Description
Gets the count of the result.

### Signature
unsigned int get_count() const

### Returns
- **unsigned int** - The count of the result.
```

--------------------------------

### scenario::scenario (constructor with ic_density)

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Constructs a scenario object with a name, number of grid points, end time, and an initial density condition.

```APIDOC
## scenario::scenario (constructor with ic_density)

### Description
Constructs a scenario object with the given name, number of grid points, end time, and initial density condition.

### Signature
scenario(const std::string &name, unsigned int num_gridpoints, real endtime, std::shared_ptr<ic_density> density_init)

### Parameters
- **name** (const std::string&) - Required - The name of the scenario.
- **num_gridpoints** (unsigned int) - Required - The number of grid points.
- **endtime** (real) - Required - The end time of the simulation.
- **density_init** (std::shared_ptr<ic_density>) - Required - The initial density condition.
```

--------------------------------

### result::get_name

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1result.html

Gets the result name.

```APIDOC
## result::get_name

### Description
Gets the result name.

### Signature
std::string get_name() const

### Returns
- **std::string** - The name of the result.
```

--------------------------------

### get_row()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1record.html

Gets row index (zero-based).

```APIDOC
## mbsolve::record::get_row()

### Description
Gets row index (zero-based).

### Returns
- **unsigned int** - Row index (zero-based).

```

--------------------------------

### solver_cpu_fdtd_red constructor

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1solver__cpu__fdtd__red.html

Constructs a solver_cpu_fdtd_red instance with a device and scenario.

```APIDOC
## solver_cpu_fdtd_red

### Description
Constructs a solver_cpu_fdtd_red instance with the given device and scenario.

### Signature
cpp
solver_cpu_fdtd_red(std::shared_ptr<const device> dev, std::shared_ptr<scenario> scen)


### Parameters
- **dev** (std::shared_ptr<const device>) - Required - The device to be used by the solver.
- **scen** (std::shared_ptr<scenario>) - Required - The scenario to be solved.

### Returns
- None (constructor)

```

--------------------------------

### get_position()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1record.html

Gets sampling position (in meter).

```APIDOC
## mbsolve::record::get_position()

### Description
Gets sampling position (in meter).

### Returns
- **real** - Sampling position in meter.

```

--------------------------------

### get_interval()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1record.html

Gets sampling interval (in seconds).

```APIDOC
## mbsolve::record::get_interval()

### Description
Gets sampling interval (in seconds).

### Returns
- **real** - Sampling interval in seconds.

```

--------------------------------

### mbsolve::solver::get_device

Source: https://mriesch-tum.github.io/mbsolve/solver_8hpp_source.html

Returns the device to be simulated. This accessor provides a constant reference to the device.

```APIDOC
## get_device

### Description
Returns the device to be simulated as a constant reference.

### Method
const

### Signature
`const device& get_device() const`

### Parameters
None

### Returns
- **const device&** - The device to be simulated.

### Example
```cpp
const device& dev = solver->get_device();
```
```

--------------------------------

### get_col()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1record.html

Gets column index (zero-based).

```APIDOC
## mbsolve::record::get_col()

### Description
Gets column index (zero-based).

### Returns
- **unsigned int** - Column index (zero-based).

```

--------------------------------

### qm_desc_2lvl constructor

Source: https://mriesch-tum.github.io/mbsolve/qm__description_8hpp_source.html

Constructs a two-level quantum description with specified parameters.

```APIDOC
## qm_desc_2lvl constructor

### Description
Constructs a two-level quantum description with specified parameters.

### Method
Constructor

### Signature
`qm_desc_2lvl(real carrier_density, real transition_freq, real dipole_moment, real scattering_rate, real dephasing_rate, real equilibrium_inversion = -1.0)`

### Parameters
- **carrier_density** (real) - Required - The density of charge carriers.
- **transition_freq** (real) - Required - The transition frequency.
- **dipole_moment** (real) - Required - The dipole moment.
- **scattering_rate** (real) - Required - The scattering rate from upper laser level to lower laser level.
- **dephasing_rate** (real) - Required - The dephasing rate.
- **equilibrium_inversion** (real) - Optional - The equilibrium population inversion. Defaults to -1.0.

### Returns
No return value (constructor).
```

--------------------------------

### get_num_gridpoints()

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Gets number of spatial grid points.

```APIDOC
## get_num_gridpoints()

### Description
Gets number of spatial grid points.

### Method
unsigned int mbsolve::scenario::get_num_gridpoints() const

### Parameters
None

### Returns
- **unsigned int** - The number of spatial grid points.
```

--------------------------------

### material::get_qm

Source: https://mriesch-tum.github.io/mbsolve/material_8hpp_source.html

Getter for the quantum mechanical description.

```APIDOC
## material::get_qm

### Description
Returns the quantum mechanical description of the active material.

### Method
Getter

### Signature
`std::shared_ptr<qm_description> get_qm() const`

### Parameters
None.

### Returns
- **std::shared_ptr<qm_description>** - The quantum mechanical description.
```

--------------------------------

### material::material

Source: https://mriesch-tum.github.io/mbsolve/material_8hpp_source.html

Constructor for the material class.

```APIDOC
## material::material

### Description
Constructs a material object with the given identifier, quantum mechanical description, and electromagnetic properties.

### Method
Constructor

### Signature
`material(const std::string& id, std::shared_ptr<qm_description> qm = nullptr, real rel_permittivity = 1.0, real overlap_factor = 1.0, real losses = 0.0, real rel_permeability = 1.0)`

### Parameters
- **id** (const std::string&) - Required - Material identifier.
- **qm** (std::shared_ptr<qm_description>) - Optional - Quantum mechanical description of the active material. Defaults to nullptr.
- **rel_permittivity** (real) - Optional - Relative permittivity. Defaults to 1.0.
- **overlap_factor** (real) - Optional - Overlap factor. Defaults to 1.0.
- **losses** (real) - Optional - Losses. Defaults to 0.0.
- **rel_permeability** (real) - Optional - Relative permeability. Defaults to 1.0.

### Returns
No return value (constructor).
```

--------------------------------

### Include mbsolve library components in lib.hpp

Source: https://mriesch-tum.github.io/mbsolve/lib_8hpp_source.html

This header file includes all necessary sub-modules for the mbsolve library, protected by the MBSOLVE_LIB_H include guard.

```cpp
/*
* mbsolve: An open-source solver tool for the Maxwell-Bloch equations.
*
* Copyright (c) 2016, Computational Photonics Group, Technical University of
* Munich.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/

#ifndef MBSOLVE_LIB_H
#define MBSOLVE_LIB_H

#include <mbsolve/lib/device.hpp>
#include <mbsolve/lib/material.hpp>
#include <mbsolve/lib/qm_description.hpp>
#include <mbsolve/lib/record.hpp>
#include <mbsolve/lib/result.hpp>
#include <mbsolve/lib/scenario.hpp>
#include <mbsolve/lib/solver.hpp>
#include <mbsolve/lib/source.hpp>
#include <mbsolve/lib/types.hpp>
#include <mbsolve/lib/writer.hpp>

#endif
```

--------------------------------

### result::get_data_complex

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1result.html

Gets the complex-valued result data.

```APIDOC
## result::get_data_complex

### Description
Gets the complex-valued result data.

### Signature
std::vector<std::complex<real>> get_data_complex() const

### Returns
- **std::vector<std::complex<real>>** - The complex-valued result data.
```

--------------------------------

### mbsolve::solver::run

Source: https://mriesch-tum.github.io/mbsolve/solver_8hpp_source.html

Runs the solver. This pure virtual method must be implemented by derived solver classes to perform the actual simulation.

```APIDOC
## run

### Description
Runs the solver. This is a pure virtual method that must be implemented by derived classes to perform the simulation.

### Method
virtual pure

### Signature
`virtual void run() const = 0`

### Parameters
None

### Returns
void

### Example
```cpp
solver->run();
```
```

--------------------------------

### source::get_value

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1source.html

Gets the source value at a given time.

```APIDOC
## source::get_value

### Description
Gets the source value at a certain time value.

### Method
`real get_value(real t, real current_value = 0.0) const`

### Parameters
- **t** (real) - Required - Time value.
- **current_value** (real) - Optional - Reserved for later use. Default is 0.0.

### Returns
- **real** - The source value at the given time.

```

--------------------------------

### scenario::get_ic_density

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Returns the initial density condition.

```APIDOC
## scenario::get_ic_density

### Description
Returns the initial density condition.

### Signature
std::shared_ptr<ic_density> get_ic_density() const

### Returns
A shared pointer to the initial density condition.
```

--------------------------------

### result::get_data_imag

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1result.html

Gets the imaginary part of the result data.

```APIDOC
## result::get_data_imag

### Description
Gets the imaginary part of the result data.

### Signature
const std::vector<real>& get_data_imag() const

### Returns
- **const std::vector<real>&** - Reference to the imaginary part of the result data.
```

--------------------------------

### Aligned memory allocation for CPU solver (mb_aligned_alloc, mb_aligned_free)

Source: https://mriesch-tum.github.io/mbsolve/common__cpu_8hpp_source.html

Provides aligned memory allocation and deallocation functions for the CPU solver. It uses Intel's _mm_malloc/_mm_free when __INTEL_COMPILER is defined, _aligned_malloc/_aligned_free on Windows, and posix_memalign/free otherwise. The __mb_assume_aligned macro is defined accordingly to hint alignment to the compiler.

```cpp
#ifdef __INTEL_COMPILER
__mb_on_device inline void*
mb_aligned_alloc(size_t size)
{
return _mm_malloc(size, ALIGN);
}

__mb_on_device inline void
mb_aligned_free(void* ptr)
{
_mm_free(ptr);
}

#define __mb_assume_aligned(ptr) __assume_aligned((ptr), ALIGN)

#else

#ifdef _WIN32

inline void*
mb_aligned_alloc(size_t size)
{
return _aligned_malloc(size, ALIGN);
}

inline void
mb_aligned_free(void* ptr)
{
_aligned_free(ptr);
}

#define __mb_assume_aligned(ptr)

#else

inline void*
mb_aligned_alloc(size_t size)
{
void* addr;
int ret;

ret = posix_memalign(&addr, ALIGN, size);

if (ret != 0) {
throw std::invalid_argument("posix_memalign failed.");
}

return addr;
}

inline void
mb_aligned_free(void* ptr)
{
free(ptr);
}

#define __mb_assume_aligned(ptr) __builtin_assume_aligned(ptr, ALIGN)

#endif

#endif
```

--------------------------------

### result::get_data_real

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1result.html

Gets the real part of the result data.

```APIDOC
## result::get_data_real

### Description
Gets the real part of the result data.

### Signature
const std::vector<real>& get_data_real() const

### Returns
- **const std::vector<real>&** - Reference to the real part of the result data.
```

--------------------------------

### mbsolve::solver::create_instance

Source: https://mriesch-tum.github.io/mbsolve/solver_8hpp_source.html

Creates a solver instance by name. This static method looks up the registered bootstrap function for the given name and invokes it with the provided device and scenario.

```APIDOC
## create_instance

### Description
Creates a solver instance of the solver registered under the given name. The method uses the registered bootstrap function to construct the solver.

### Method
static

### Signature
`static std::shared_ptr<solver> create_instance(const std::string& name, std::shared_ptr<const device> dev, std::shared_ptr<scenario> scen)`

### Parameters
- **name** (const std::string&) - Required - The name of the solver to create.
- **dev** (std::shared_ptr<const device>) - Required - The device to be simulated.
- **scen** (std::shared_ptr<scenario>) - Required - The simulation scenario.

### Returns
- **std::shared_ptr<solver>** - A shared pointer to the created solver instance.

### Example
```cpp
auto solver = mbsolve::solver::create_instance("my_solver", dev, scen);
```
```

--------------------------------

### qm_operator::get_num_levels

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1qm__operator.html

Gets the number of levels of the quantum operator.

```APIDOC
## Method

### Description
Gets number of levels.

### Signature
unsigned int get_num_levels() const

### Returns
- **unsigned int** - The number of levels
```

--------------------------------

### get_qm_constants method

Source: https://mriesch-tum.github.io/mbsolve/algo__lindblad__cvr__rodr_8hpp_source.html

Determines the simulation constants for the quantum mechanical description required for the generalized Rodrigues formula.

```cpp
static sim_constants get_qm_constants(
std::shared_ptr<const qm_description> qm,
real time_step)
{
sim_constants sc;

if (qm) {
/* quantum mechanical description present */
sc.has_qm = true;
```

--------------------------------

### qm_operator::get_main_diagonal

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1qm__operator.html

Gets the main diagonal entries of the quantum operator.

```APIDOC
## Method

### Description
Gets main diagonal entries.

### Signature
const std::vector<real>& get_main_diagonal() const

### Returns
- **const std::vector<real>&** - The main diagonal entries
```

--------------------------------

### real get_minimum_permittivity() const

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1device.html

Gets the minimum relative permittivity value.

```APIDOC
## real get_minimum_permittivity() const

### Description
Gets the minimum relative permittivity value.

### Returns
The minimum relative permittivity as a real number.

```

--------------------------------

### FDTD common header with simulation initialization and constants

Source: https://mriesch-tum.github.io/mbsolve/common__fdtd_8hpp_source.html

Header guard and includes for the FDTD common utilities. Defines the sim_source struct, the init_fdtd_simulation function, the sim_constants_fdtd struct, and the get_fdtd_constants function within the mbsolve namespace.

```cpp
#ifndef MBSOLVE_COMMON_FDTD_H
#define MBSOLVE_COMMON_FDTD_H

#include <memory>
#include <mbsolve/lib/device.hpp>
#include <mbsolve/lib/scenario.hpp>
#include <mbsolve/lib/source.hpp>
#include <mbsolve/lib/types.hpp>

namespace mbsolve {

class sim_source
{
public:
 source::type type;
 unsigned int x_idx;
 unsigned int data_base_idx;
};

static void
init_fdtd_simulation(
 std::shared_ptr<const device> dev,
 std::shared_ptr<scenario> scen,
 real courant = 1)
{
 if (scen->get_num_gridpoints() > 0) {
 /* speed of light (use smallest value of relative permittivities) */
 real velocity =
 1.0 / sqrt(MU0 * EPS0 * dev->get_minimum_permittivity());

 /* get number of grid points */
 unsigned int n_x = scen->get_num_gridpoints();

 /* grid point size */
 real d_x = dev->get_length() / (n_x - 1);
 scen->set_gridpoint_size(d_x);

 /* time step size */
 real d_t = courant * d_x / velocity;

 /* number of time steps */
 unsigned int n_t = ceil(scen->get_endtime() / d_t) + 1;
 scen->set_num_timesteps(n_t);

 /* re-adjust time step size in order to fit number of time steps */
 d_t = scen->get_endtime() / (n_t - 1);
 scen->set_timestep_size(d_t);

 } else {
 throw std::invalid_argument("Invalid scenario.");
 }
}

class sim_constants_fdtd
{
public:
 /* prefactor for current electric field in Ampere's law (update equation
 * for electric field).
 */
 real fac_a;

 /* prefactor for the \partial_x H_y and \partial_t P_z (update equation
 * for electric field)
 */
 real fac_b;

 /* prefactor for \partial_x E_z (update equation for magnetic field) */
 real fac_c;

 /* overlap factor (applied as pre-factor to polarization, which is
 * determined by the density matrix)
 */
 real gamma;
};

static sim_constants_fdtd
get_fdtd_constants(
 std::shared_ptr<const device> dev,
 std::shared_ptr<const scenario> scen,
 std::shared_ptr<const material> mat)
{
 sim_constants_fdtd sc;

 /* convert loss term to conductivity */
 real sigma = sqrt(
 EPS0 * mat->get_rel_permittivity() /
 (MU0 * mat->get_rel_permeability())) *
 mat->get_losses() * 2.0;

 real dt = scen->get_timestep_size();
 real epsilon = EPS0 * mat->get_rel_permittivity();
 real x = (sigma * dt) / (2.0 * epsilon);

 /* prefactor a */
 sc.fac_a = (1.0 - x) / (1.0 + x);

 /* prefactor b */
 sc.fac_b = dt / epsilon / (1.0 + x);

 /* prefactor c */
 sc.fac_c =
 dt / (MU0 * mat->get_rel_permeability() * scen->get_gridpoint_size());

 /* overlap factor */
 sc.gamma = mat->get_overlap_factor();

 return sc;
}
}

#endif
```

--------------------------------

### scenario::add_source

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Adds a source to the scenario.

```APIDOC
## scenario::add_source

### Description
Adds a source to the scenario.

### Signature
void add_source(std::shared_ptr<source> src)

### Parameters
- **src** (std::shared_ptr<source>) - Required - The source to add.
```

--------------------------------

### scenario::add_source

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Adds a source to the scenario.

```APIDOC
## scenario::add_source

### Description
Adds a source to the scenario.

### Signature
void mbsolve::scenario::add_source(std::shared_ptr< source > _src_)

### Parameters
- **src** (std::shared_ptr< source >) - The source to add.
```

--------------------------------

### result::get_data_imag_it

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1result.html

Gets an iterator for the imaginary part of the result data at a specified row and column.

```APIDOC
## result::get_data_imag_it

### Description
Gets an iterator for the imaginary part of the result data.

### Signature
std::vector<real>::iterator get_data_imag_it(unsigned int row, unsigned int col)

### Parameters
- **row** (unsigned int) - Required - Row index.
- **col** (unsigned int) - Required - Column index.

### Returns
- **std::vector<real>::iterator** - Iterator for the imaginary part of the result data.
```

--------------------------------

### result::get_data_real_it

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1result.html

Gets an iterator for the real part of the result data at a specified row and column.

```APIDOC
## result::get_data_real_it

### Description
Gets an iterator for the real part of the result data.

### Signature
std::vector<real>::iterator get_data_real_it(unsigned int row, unsigned int col)

### Parameters
- **row** (unsigned int) - Required - Row index.
- **col** (unsigned int) - Required - Column index.

### Returns
- **std::vector<real>::iterator** - Iterator for the real part of the result data.
```

--------------------------------

### source::source

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1source.html

Constructs a source with the given name, position, type, amplitude, frequency, and optional phase.

```APIDOC
## source::source

### Description
Constructs a source with the specified parameters.

### Constructor
`source(const std::string &name, real position, type source_type, real ampl, real freq, real phase = 0)`

### Parameters
- **name** (std::string) - Required - Name of the source.
- **position** (real) - Required - Position of the source (in meters).
- **source_type** (type) - Required - Source type (hard_source or soft_source).
- **ampl** (real) - Required - Amplitude of the source.
- **freq** (real) - Required - Frequency of the source.
- **phase** (real) - Optional - Phase of the source. Default is 0.

```

--------------------------------

### material::get_id

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1material.html

Gets the material ID. This is a const member function that returns the identifier of the material.

```APIDOC
## material::get_id

### Description
Gets the material ID. This is a const member function that returns the identifier of the material.

### Method
Member Function

### Signature
`const std::string& mbsolve::material::get_id() const`

### Returns
- **const std::string&** - The material ID.

### Example
```cpp
// Get the material ID
std::string id = mat->get_id();
```
```

--------------------------------

### record() [2/2]

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1record.html

Constructor that constructs a record with explicit type, row, and column indices.

```APIDOC
## mbsolve::record::record [2/2]

### Description
Constructs record with explicit type, row index, and column index.

### Parameters
- **name** (const std::string&) - [in] - Name of the record.
- **record_type** (type) - [in] - Type of the record, e.g., "density".
- **row_idx** (unsigned int) - [in] - Only for density matrix entries. One-based.
- **col_idx** (unsigned int) - [in] - Only for density matrix entries. One-based.
- **interval** (real) - [in] - Sampling interval in seconds. If set to 0.0, the value at every time step is stored.
- **position** (real) - [in] - Sampling position in meter. If set to -1.0, the complete grid is stored.

```

--------------------------------

### scenario::set_ic_density

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1scenario.html

Sets the initial density condition.

```APIDOC
## scenario::set_ic_density

### Description
Sets the initial density condition.

### Signature
void set_ic_density(std::shared_ptr<ic_density> density_init)

### Parameters
- **density_init** (std::shared_ptr<ic_density>) - Required - The initial density condition to set.
```

--------------------------------

### writer_hdf5_loader constructor

Source: https://mriesch-tum.github.io/mbsolve/writer__hdf5_8hpp_source.html

Constructs a writer_hdf5_loader object. This is the default constructor for the writer_hdf5_loader class.

```APIDOC
## writer_hdf5_loader::writer_hdf5_loader

### Description
Constructs a writer_hdf5_loader object. This is the default constructor for the writer_hdf5_loader class.

### Method
writer_hdf5_loader

### Signature
writer_hdf5_loader()

### Parameters
None

### Return Value
None
```

--------------------------------

### Utility Functions for Density and Population

Source: https://mriesch-tum.github.io/mbsolve/algo__lindblad__cvr__rodr_8hpp_source.html

Provides helper functions to calculate population inversion, specific populations, and convert operators to density matrices.

```cpp
/*
* Returns the population inversion (which is the difference
* \f$ \rho_{22} - \rho_{11} \f$).
*/
static inline real calc_inversion(const density& d)
{
return d(num_lvl * (num_lvl - 1));
}

/*
* Returns the population specified by \param idx (zero-based).
*/
static inline real calc_population(const density& d, unsigned int idx)
{
return cv_representation::calc_population<num_lvl, vec_len>(d, idx);
}

/*
* Converts the density matrix \param op into the coherence vector
* representation.
*/
static inline density get_density(const qm_operator& op)
{
return cv_representation::coherence_vector<num_lvl, vec_len>(op);
}

/*
* Returns a zero coherence vector (for initialization purposes only).
*/
static inline density get_density() { return density::Zero(); }
```

--------------------------------

### qm_operator::get_off_diagonal

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1qm__operator.html

Gets the off-diagonal entries (top half, column major ordering) of the quantum operator.

```APIDOC
## Method

### Description
Gets off-diagonal entries (top half, column major ordering).

### Signature
const std::vector<std::complex<real>>& get_off_diagonal() const

### Returns
- **const std::vector<std::complex<real>>&** - The off-diagonal entries
```

--------------------------------

### mbsolve::writer::create_instance

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1writer.html

Static function that constructs a writer instance with a given name.

```APIDOC
## mbsolve::writer::create_instance

### Description
Constructs a writer with a given name.

### Method
create_instance

### Signature
static std::shared_ptr<writer> create_instance(const std::string &name)

### Parameters
- **name** (const std::string&) - Required - Name of the writer method.

### Returns
std::shared_ptr<writer> - A shared pointer to the created writer instance.
```

--------------------------------

### material::get_losses

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1material.html

Gets the optical losses α. This is a const member function that returns the losses value.

```APIDOC
## material::get_losses

### Description
Gets the optical losses α. This is a const member function that returns the losses value.

### Method
Member Function

### Signature
`real mbsolve::material::get_losses() const`

### Returns
- **real** - The optical losses α.

### Example
```cpp
// Get the losses
real losses = mat->get_losses();
```
```

--------------------------------

### material::get_rel_permittivity

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1material.html

Gets the relative permittivity εr. This is a const member function that returns the relative permittivity value.

```APIDOC
## material::get_rel_permittivity

### Description
Gets the relative permittivity εr. This is a const member function that returns the relative permittivity value.

### Method
Member Function

### Signature
`real mbsolve::material::get_rel_permittivity() const`

### Returns
- **real** - The relative permittivity εr.

### Example
```cpp
// Get the relative permittivity
real eps_r = mat->get_rel_permittivity();
```
```

--------------------------------

### material::get_rel_permeability

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1material.html

Gets the relative permeability μr. This is a const member function that returns the relative permeability value.

```APIDOC
## material::get_rel_permeability

### Description
Gets the relative permeability μr. This is a const member function that returns the relative permeability value.

### Method
Member Function

### Signature
`real mbsolve::material::get_rel_permeability() const`

### Returns
- **real** - The relative permeability μr.

### Example
```cpp
// Get the relative permeability
real mu_r = mat->get_rel_permeability();
```
```

--------------------------------

### record::record (constructor with name, interval, position)

Source: https://mriesch-tum.github.io/mbsolve/record_8hpp_source.html

Constructs a record object with a name, optional interval, and optional position. This constructor is used for recording data at a specific position or over an interval.

```APIDOC
## record::record (constructor)

### Description
Constructs a record object with a name, optional interval, and optional position. This constructor is used for recording data at a specific position or over an interval.

### Method
Constructor

### Signature
`record(const std::string& name, real interval = 0.0, real position = -1.0)`

### Parameters
- **name** (const std::string&) - Required - The name of the record.
- **interval** (real) - Optional - The recording interval. Default is 0.0.
- **position** (real) - Optional - The position for recording. Default is -1.0.

### Returns
No return value (constructor).
```

--------------------------------

### material::get_overlap_factor

Source: https://mriesch-tum.github.io/mbsolve/classmbsolve_1_1material.html

Gets the overlap factor Γ. This is a const member function that returns the overlap factor value.

```APIDOC
## material::get_overlap_factor

### Description
Gets the overlap factor Γ. This is a const member function that returns the overlap factor value.

### Method
Member Function

### Signature
`real mbsolve::material::get_overlap_factor() const`

### Returns
- **real** - The overlap factor Γ.

### Example
```cpp
// Get the overlap factor
real overlap = mat->get_overlap_factor();
```
```