FFTW

https://docs.rs/fftw/latest
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FFTW is a fast C library for computing the Discrete Fourier Transform (DFT), with a Rust binding...
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### Slice::len Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Demonstrates how to get the number of elements in a slice.

```rust
let a = [1, 2, 3];
assert_eq!(a.len(), 3);
```

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

### Get Metadata with Path and Handle Errors

Source: https://docs.rs/fftw/latest/fftw/error/type.Result.html

Shows how to get file metadata using Path and handle potential errors, such as non-existent paths.

```rust
use std::{io::ErrorKind, path::Path};

// Note: on Windows "/" maps to "C:\"
let root_modified_time = Path::new("/").metadata().and_then(|md| md.modified());
assert!(root_modified_time.is_ok());

let should_fail = Path::new("/bad/path").metadata().and_then(|md| md.modified());
assert!(should_fail.is_err());
assert_eq!(should_fail.unwrap_err().kind(), ErrorKind::NotFound);
```

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

### Complex-to-Real Transformation Example

Source: https://docs.rs/fftw/latest/fftw/index.html

Demonstrates how to perform a complex-to-real Fast Fourier Transform using the fftw crate.

```APIDOC
## Complex-to-Real Transformation

### Description
Performs a complex-to-real Fast Fourier Transform.

### Method
`c2r`

### Endpoint
N/A (Library function)

### Parameters
N/A (Library function)

### Request Example
```rust
use fftw::array::AlignedVec;
use fftw::plan::C2RPlan;
use fftw::types::C64;
use std::f64::consts::PI;

let n = 128;
let mut c2r: fftw::plan::C2RPlan64 = C2RPlan::aligned(&[n], fftw::flag::Flag::MEASURE).unwrap();
let mut a = AlignedVec::new(n / 2 + 1);
let mut b = AlignedVec::new(n);
for i in 0..(n / 2 + 1) {
    a[i] = c64::new(1.0, 0.0);
}
c2r.c2r(&mut a, &mut b).unwrap();
```

### Response
N/A (Library function)

### Response Example
N/A (Library function)
```

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

### Complex-to-Complex Transformation Example

Source: https://docs.rs/fftw/latest/fftw/index.html

Demonstrates how to perform a complex-to-complex Fast Fourier Transform using the fftw crate.

```APIDOC
## Complex-to-Complex Transformation

### Description
Performs a complex-to-complex Fast Fourier Transform.

### Method
`c2c`

### Endpoint
N/A (Library function)

### Parameters
N/A (Library function)

### Request Example
```rust
use fftw::array::AlignedVec;
use fftw::plan::C2CPlan;
use fftw::types::{C64, Sign};
use std::f64::consts::PI;

let n = 128;
let mut plan: fftw::plan::C2CPlan64 = C2CPlan::aligned(&[n], Sign::Forward, fftw::flag::Flag::MEASURE).unwrap();
let mut a = AlignedVec::new(n);
let mut b = AlignedVec::new(n);
let k0 = 2.0 * PI / n as f64;
for i in 0..n {
    a[i] = c64::new((k0 * i as f64).cos(), 0.0);
}
plan.c2c(&mut a, &mut b).unwrap();
```

### Response
N/A (Library function)

### Response Example
N/A (Library function)
```

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

### Slice::split_first Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Splits a slice into its first element and the rest of the slice.

```rust
let x = &[0, 1, 2];

if let Some((first, elements)) = x.split_first() {
    assert_eq!(first, &0);
    assert_eq!(elements, &[1, 2]);
}
```

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

### Slice::is_empty Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Shows how to check if a slice is empty.

```rust
let a = [1, 2, 3];
assert!(!a.is_empty());

let b: &[i32] = &[];
assert!(b.is_empty());
```

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

### Slice Starts With Method

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Checks if a slice begins with a specified prefix slice.

```APIDOC
## GET /slice/starts_with

### Description
Returns `true` if `needle` is a prefix of the slice or equal to the slice. Always returns `true` if `needle` is an empty slice.

### Method
GET

### Endpoint
`/slice/starts_with`

### Parameters
#### Query Parameters
- **slice** (array) - Required - The slice to check.
- **needle** (array) - Required - The prefix slice to compare against.

### Request Example
```json
{
  "slice": [10, 40, 30],
  "needle": [10, 40]
}
```

### Response
#### Success Response (200)
- **result** (boolean) - `true` if the slice starts with the needle, `false` otherwise.

#### Response Example
```json
{
  "result": true
}
```
```

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

### Display and Default Implementations

Source: https://docs.rs/fftw/latest/fftw/types/type.c64.html

Shows how Complex numbers can be formatted for display and how to get their default value.

```APIDOC
## Display for Complex<T>

### Description
Implements the `Display` trait for `Complex<T>`, allowing it to be formatted using a formatter.

### Method
`fmt`

### Parameters
- `f` (*Formatter<'_>*) - A mutable reference to a formatter.

### Response
- `Result<(), Error>` - Indicates success or failure of the formatting operation.

## Default for Complex<T>

### Description
Implements the `Default` trait for `Complex<T>`.

### Method
`default`

### Response
- `Complex<T>` - Returns the default value for `Complex<T>`.
```

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

### Slice::first Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Retrieves the first element of a slice if it exists.

```rust
let v = [10, 40, 30];
assert_eq!(Some(&10), v.first());

let w: &[i32] = &[];
assert_eq!(None, w.first());
```

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

### Slice::split_first_mut Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Splits a mutable slice into its first element and the rest of the slice.

```rust
let x = &mut [0, 1, 2];

if let Some((first, elements)) = x.split_first_mut() {
    *first = 3;
    elements[0] = 4;
    elements[1] = 5;
}
assert_eq!(x, &[3, 4, 5]);
```

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

### Slice::split_last Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Splits a slice into its last element and the preceding elements.

```rust
let x = &[0, 1, 2];

if let Some((last, elements)) = x.split_last() {
    assert_eq!(last, &2);
    assert_eq!(elements, &[0, 1]);
}
```

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

### Use `unwrap_or_else` with a Closure

Source: https://docs.rs/fftw/latest/fftw/error/type.Result.html

Demonstrates getting the `Ok` value or computing a default value using a closure if the Result is an `Err`.

```rust
fn count(x: &str) -> usize { x.len() }

assert_eq!(Ok(2).unwrap_or_else(count), 2);
assert_eq!(Err("foo").unwrap_or_else(count), 3);
```

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

### Providing a Default Value with `unwrap_or`

Source: https://docs.rs/fftw/latest/fftw/error/type.Result.html

Demonstrates how to get the `Ok` value or a default value if the `Result` is `Err` using `unwrap_or`.

```APIDOC
## `unwrap_or` Example

### Description
Returns the contained `Ok` value or a provided default. Arguments passed to `unwrap_or` are eagerly evaluated.

### Method
`unwrap_or`

### Endpoint
N/A (Method on `Result` type)

### Request Body
N/A

### Request Example
```rust
let default = 2;
let x: Result<u32, &str> = Ok(9);
assert_eq!(x.unwrap_or(default), 9);

let x: Result<u32, &str> = Err("error");
assert_eq!(x.unwrap_or(default), default);
```

### Response
#### Success Response
Returns the `Ok` value if `self` is `Ok`.

#### Response Example
```rust
9
```

#### Default Value Response
Returns the `default` value if `self` is `Err`.

#### Response Example
```rust
2
```
```

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

### Check if a slice starts with a prefix

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Use `starts_with` to verify if a slice begins with a specific sequence of elements. It always returns `true` if the `needle` is an empty slice.

```rust
let v = [10, 40, 30];
assert!(v.starts_with(&[10]));
assert!(v.starts_with(&[10, 40]));
assert!(v.starts_with(&v));
assert!(!v.starts_with(&[50]));
assert!(!v.starts_with(&[10, 50]));
```

```rust
let v = &[10, 40, 30];
assert!(v.starts_with(&[]));
let v: &[u8] = &[];
assert!(v.starts_with(&[]));
```

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

### FFTW Complex-to-Real Transformation

Source: https://docs.rs/fftw/latest/fftw/index.html

Performs a complex-to-real Fast Fourier Transform using FFTW. Requires specific imports and setup.

```rust
use fftw::array::AlignedVec;
use fftw::plan::*;
use fftw::types::*;
use std::f64::consts::PI;

let n = 128;
let mut c2r: C2RPlan64 = C2RPlan::aligned(&[n], Flag::MEASURE).unwrap();
let mut a = AlignedVec::new(n / 2 + 1);
let mut b = AlignedVec::new(n);
for i in 0..(n / 2 + 1) {
    a[i] = c64::new(1.0, 0.0);
}
c2r.c2r(&mut a, &mut b).unwrap();

```

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

### Slice::first_chunk Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns an array reference to the first N items in the slice. Returns None if the slice is shorter than N.

```rust
let u = [10, 40, 30];
assert_eq!(Some(&[10, 40]), u.first_chunk::<2>());

let v: &[i32] = &[10];
assert_eq!(None, v.first_chunk::<2>());

let w: &[i32] = &[];
assert_eq!(Some(&[]), w.first_chunk::<0>());
```

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

### Use `unwrap_or` with a Default Value

Source: https://docs.rs/fftw/latest/fftw/error/type.Result.html

Shows how to get the `Ok` value or a provided default value if the Result is an `Err`. The default is eagerly evaluated.

```rust
let default = 2;
let x: Result<u32, &str> = Ok(9);
assert_eq!(x.unwrap_or(default), 9);

let x: Result<u32, &str> = Err("error");
assert_eq!(x.unwrap_or(default), default);
```

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

### Iterate Over Slice Elements in Rust

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Use `iter()` to get an immutable iterator over slice elements. The iterator yields items from start to end.

```rust
let x = &[1, 2, 4];
let mut iterator = x.iter();

assert_eq!(iterator.next(), Some(&1));
assert_eq!(iterator.next(), Some(&2));
assert_eq!(iterator.next(), Some(&4));
assert_eq!(iterator.next(), None);
```

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

### C2RPlan new Method

Source: https://docs.rs/fftw/latest/fftw/plan/trait.C2RPlan.html

Creates a new complex-to-real plan. Requires shape, input complex slice, output real slice, and transformation flags.

```rust
fn new(
        shape: &[usize],
        in_: &mut [Self::Complex],
        out: &mut [Self::Real],
        flag: Flag,
    ) -> Result<Self>
```

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

### Plan<A, B, Plan> Implementations

Source: https://docs.rs/fftw/latest/fftw/plan/struct.Plan.html

Shows blanket implementations for Plan<A, B, Plan> for various traits.

```APIDOC
## impl<A, B, Plan> Freeze for Plan<A, B, Plan>

### Description
Blanket implementation of the Freeze trait for Plan<A, B, Plan>.

### Method
N/A (Blanket Implementation)

### Endpoint
N/A

## impl<A, B, Plan> RefUnwindSafe for Plan<A, B, Plan>

### Description
Blanket implementation of the RefUnwindSafe trait for Plan<A, B, Plan>.

### Method
N/A (Blanket Implementation)

### Endpoint
N/A

## impl<A, B, Plan> !Send for Plan<A, B, Plan>

### Description
Blanket implementation of the !Send trait (negated Send) for Plan<A, B, Plan>.

### Method
N/A (Blanket Implementation)

### Endpoint
N/A

## impl<A, B, Plan> Sync for Plan<A, B, Plan>

### Description
Blanket implementation of the Sync trait for Plan<A, B, Plan>.

### Method
N/A (Blanket Implementation)

### Endpoint
N/A

## impl<A, B, Plan> Unpin for Plan<A, B, Plan>

### Description
Blanket implementation of the Unpin trait for Plan<A, B, Plan>.

### Method
N/A (Blanket Implementation)

### Endpoint
N/A

## impl<A, B, Plan> UnwindSafe for Plan<A, B, Plan>

### Description
Blanket implementation of the UnwindSafe trait for Plan<A, B, Plan>.

### Method
N/A (Blanket Implementation)

### Endpoint
N/A
```

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

### rchunks

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns an iterator over chunk_size elements starting at the end.

```APIDOC
## rchunks

### Description
Returns an iterator over `chunk_size` elements of the slice at a time, starting at the end of the slice. The chunks are slices and do not overlap.

### Parameters
- **chunk_size** (usize) - Required - The size of the chunks.

### Panics
- Panics if `chunk_size` is zero.
```

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

### Slice::split_first_chunk Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns an array reference to the first N items in the slice and the remaining slice. Returns None if the slice is shorter than N.

```rust
pub fn split_first_chunk<const N: usize>(&self) -> Option<(&[T; N], &[T])>
```

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

### pub fn windows(&self, size: usize)

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns an iterator over all contiguous windows of length size.

```APIDOC
## pub fn windows(&self, size: usize)

### Description
Returns an iterator over all contiguous windows of length `size`. The windows overlap. If the slice is shorter than `size`, the iterator returns no values.

### Parameters
#### Path Parameters
- **size** (usize) - Required - The length of the windows.
```

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

### as_rchunks_mut

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Splits the slice into a slice of N-element arrays starting from the end.

```APIDOC
## as_rchunks_mut

### Description
Splits the slice into a slice of `N`-element arrays, starting at the end of the slice, and a remainder slice with length strictly less than `N`.

### Parameters
- **N** (const usize) - Required - The size of the chunks.

### Panics
- Panics if `N` is zero.
```

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

### Slice::last Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Retrieves the last element of a slice if it exists.

```rust
let v = [10, 40, 30];
assert_eq!(Some(&30), v.last());

let w: &[i32] = &[];
assert_eq!(None, w.last());
```

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

### R2RPlan32::new

Source: https://docs.rs/fftw/latest/fftw/plan/type.R2RPlan32.html

Creates a new real-to-real plan for 32-bit floating point data.

```APIDOC
## R2RPlan32::new

### Description
Creates a new real-to-real plan for 32-bit floating point data.

### Parameters
- **shape** (&[usize]) - Required - The dimensions of the transform.
- **in_** (&mut [f32]) - Required - Input buffer.
- **out_** (&mut [f32]) - Required - Output buffer.
- **kind** (R2RKind) - Required - The type of R2R transform.
- **flag** (Flag) - Required - FFTW planning flags.

### Response
- **Result<Self>** - Returns the new plan or an error.
```

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

### Retrieve Slice Metadata

Source: https://docs.rs/fftw/latest/src/fftw/plan.rs.html

Utility function to get the length and alignment of a slice.

```rust
fn slice_info<T>(a: &[T]) -> (usize, Alignment) {
    (a.len(), alignment_of(a))
}
```

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

### FFTW Flag Initialization Methods

Source: https://docs.rs/fftw/latest/fftw/types/struct.Flag.html

Methods for creating Flag values, including empty, all flags, and from bit representations.

```rust
pub const fn empty() -> Self
```

```rust
pub const fn all() -> Self
```

```rust
pub const fn from_bits(bits: u32) -> Option<Self>
```

```rust
pub const fn from_bits_truncate(bits: u32) -> Self
```

```rust
pub const fn from_bits_retain(bits: u32) -> Self
```

```rust
pub fn from_name(name: &str) -> Option<Self>
```

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

### R2RPlan::new

Source: https://docs.rs/fftw/latest/fftw/plan/trait.R2RPlan.html

Creates a new real-to-real transform plan.

```APIDOC
## fn new

### Description
Creates a new plan for a real-to-real transform.

### Parameters
- **shape** (&[usize]) - Required - The dimensions of the transform.
- **in_** (&mut [Self::Real]) - Required - Input buffer.
- **out_** (&mut [Self::Real]) - Required - Output buffer.
- **kind** (R2RKind) - Required - The type of R2R transform.
- **flag** (Flag) - Required - FFTW planning flags.

### Response
- **Result<Self>** - Returns the new plan or an error if creation fails.
```

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

### C2RPlan64 API

Source: https://docs.rs/fftw/latest/fftw/plan/type.C2RPlan64.html

Methods for creating and executing complex-to-real FFTW plans.

```APIDOC
## C2RPlan64

### Description
A type alias for Plan<c64, f64, Plan64> used to perform complex-to-real transforms.

### Methods
- **new(shape: &[usize], in_: &mut [Self::Complex], out: &mut [Self::Real], flag: Flag) -> Result<Self>**
  Creates a new plan for the specified shape and buffers.
- **c2r(&mut self, in_: &mut [Self::Complex], out: &mut [Self::Real]) -> Result<()>**
  Executes the complex-to-real transform using the provided buffers.
- **aligned(shape: &[usize], flag: Flag) -> Result<Self>**
  Creates a new plan with aligned vector memory allocation.
```

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

### C2RPlan::c2r

Source: https://docs.rs/fftw/latest/fftw/plan/trait.C2RPlan.html

Executes the complex-to-real transformation using the initialized plan.

```APIDOC
## fn c2r

### Description
Executes the complex-to-real transform on the provided buffers.

### Parameters
- **in_** (&mut [Self::Complex]) - Required - Input buffer for complex data.
- **out** (&mut [Self::Real]) - Required - Output buffer for real data.

### Response
- **Result<()>** - Returns Ok(()) on success or an error.
```

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

### Get Imaginary Unit

Source: https://docs.rs/fftw/latest/fftw/types/type.c64.html

Returns the imaginary unit `i`. This is an alternative to the `Complex::I` constant.

```rust
pub fn i() -> Complex<T>;
```

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

### Slice::last_mut Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Provides mutable access to the last element of a slice, if it exists.

```rust
let x = &mut [0, 1, 2];

if let Some(last) = x.last_mut() {
    *last = 10;
}
assert_eq!(x, &[0, 1, 10]);

let y: &mut [i32] = &mut [];
assert_eq!(None, y.last_mut());
```

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

### R2RPlan new Method

Source: https://docs.rs/fftw/latest/fftw/plan/trait.R2RPlan.html

Creates a new R2RPlan. Requires specifying the shape of the transform, input and output buffers, the type of transform (R2RKind), and FFTW flags.

```rust
fn new(
        shape: &[usize],
        in_: &mut [Self::Real],
        out: &mut [Self::Real],
        kind: R2RKind,
        flag: Flag,
    ) -> Result<Self>
```

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

### Slice::split_last_mut Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Splits a mutable slice into its last element and the preceding elements.

```rust
let x = &mut [0, 1, 2];

if let Some((last, elements)) = x.split_last_mut() {
    *last = 3;
    elements[0] = 4;
    elements[1] = 5;
}
assert_eq!(x, &[4, 5, 3]);
```

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

### Perform Complex-to-Real FFT

Source: https://docs.rs/fftw/latest/index.html

Demonstrates executing a complex-to-real transform using an aligned C2RPlan.

```rust
use fftw::array::AlignedVec;
use fftw::plan::*;
use fftw::types::*;
use std::f64::consts::PI;

let n = 128;
let mut c2r: C2RPlan64 = C2RPlan::aligned(&[n], Flag::MEASURE).unwrap();
let mut a = AlignedVec::new(n / 2 + 1);
let mut b = AlignedVec::new(n);
for i in 0..(n / 2 + 1) {
    a[i] = c64::new(1.0, 0.0);
}
c2r.c2r(&mut a, &mut b).unwrap();
```

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

### Perform Complex-to-Complex FFT

Source: https://docs.rs/fftw/latest/index.html

Demonstrates setting up an aligned plan and executing a forward complex-to-complex transform on an AlignedVec.

```rust
use fftw::array::AlignedVec;
use fftw::plan::*;
use fftw::types::*;
use std::f64::consts::PI;

let n = 128;
let mut plan: C2CPlan64 = C2CPlan::aligned(&[n], Sign::Forward, Flag::MEASURE).unwrap();
let mut a = AlignedVec::new(n);
let mut b = AlignedVec::new(n);
let k0 = 2.0 * PI / n as f64;
for i in 0..n {
    a[i] = c64::new((k0 * i as f64).cos(), 0.0);
}
plan.c2c(&mut a, &mut b).unwrap();
```

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

### Slice::first_mut Example

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Provides mutable access to the first element of a slice, if it exists.

```rust
let x = &mut [0, 1, 2];

if let Some(first) = x.first_mut() {
    *first = 5;
}
assert_eq!(x, &[5, 1, 2]);

let y: &mut [i32] = &mut [];
assert_eq!(None, y.first_mut());
```

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

### SIMD Slice Splitting with as_simd

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Illustrates splitting a slice into prefix, middle (SIMD types), and suffix using `as_simd`. This is a nightly-only experimental API. It handles cases where there aren't enough elements for a full SIMD type.

```rust
#![feature(portable_simd)]
use core::simd::prelude::*;

let short = &[1, 2, 3];
let (prefix, middle, suffix) = short.as_simd::<4>();
assert_eq!(middle, []); // Not enough elements for anything in the middle

// They might be split in any possible way between prefix and suffix
let it = prefix.iter().chain(suffix).copied();
assert_eq!(it.collect::<Vec<_>>(), vec![1, 2, 3]);

fn basic_simd_sum(x: &[f32]) -> f32 {
    use std::ops::Add;
    let (prefix, middle, suffix) = x.as_simd();
    let sums = f32x4::from_array([
        prefix.iter().copied().sum(),
        0.0,
        0.0,
        suffix.iter().copied().sum(),
    ]);
    let sums = middle.iter().copied().fold(sums, f32x4::add);
    sums.reduce_sum()
}

let numbers: Vec<f32> = (1..101).map(|x| x as _).collect();
assert_eq!(basic_simd_sum(&numbers[1..99]), 4949.0);
```

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

### Split slice from the end

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Splits a slice into a remainder and fixed-size arrays starting from the end of the slice.

```rust
let slice = ['l', 'o', 'r', 'e', 'm'];
let (remainder, chunks) = slice.as_rchunks();
assert_eq!(remainder, &['l']);
assert_eq!(chunks, &[['o', 'r'], ['e', 'm']]);
```

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

### Plan64 Trait Implementations

Source: https://docs.rs/fftw/latest/fftw/plan/type.Plan64.html

Provides details on the trait implementations for the Plan64 type.

```APIDOC
## Trait Implementations for Plan64

### `impl PlanSpec for Plan64`

#### `fn validate(self) -> Result<Self>`

Validates the plan.

#### `fn destroy(self)`

Destroys the plan.

#### `fn print(self)`

Prints the plan.
```

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

### pub fn iter(&self)

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns an iterator over the slice yielding all items from start to end.

```APIDOC
## pub fn iter(&self)

### Description
Returns an iterator over the slice. The iterator yields all items from start to end.

### Parameters
#### Path Parameters
- **self** - Required - The slice to iterate over.
```

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

### C2RPlan::aligned

Source: https://docs.rs/fftw/latest/fftw/plan/trait.C2RPlan.html

Creates a new plan with aligned memory allocation.

```APIDOC
## fn aligned

### Description
Creates a new plan with aligned vector allocation.

### Parameters
- **shape** (&[usize]) - Required - The shape of the transformation.
- **flag** (Flag) - Required - FFTW planning flags.

### Response
- **Result<Self>** - Returns the initialized plan or an error.
```

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

### get

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns a reference to an element or subslice depending on the type of index. Returns None if the index is out of bounds.

```APIDOC
## get<I>

### Description
Returns a reference to an element or subslice depending on the type of index. If given a position, returns a reference to the element at that position or `None` if out of bounds. If given a range, returns the subslice corresponding to that range, or `None` if out of bounds.

### Method
GET (conceptual)

### Endpoint
N/A (method on slice)

### Parameters
#### Path Parameters
- **index** (I: SliceIndex<[T]>) - Required - The index or range to access.

### Request Example
```rust
let v = [10, 40, 30];
assert_eq!(Some(&40), v.get(1));
assert_eq!(Some(&[10, 40][..]), v.get(0..2));
assert_eq!(None, v.get(3));
assert_eq!(None, v.get(0..4));
```

### Response
#### Success Response (200)
- **Option<&<I as SliceIndex<[T]>>::Output>** - A reference to the element or subslice, or None if out of bounds.

#### Response Example
```json
// Conceptual representation of accessing an element
{
  "value": 40
}
// Conceptual representation of accessing a subslice
{
  "subslice": [10, 40]
}
```
```

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

### Plan<c64, c64, Plan64> Trait Implementations

Source: https://docs.rs/fftw/latest/fftw/plan/type.C2CPlan64.html

Provides implementations for the Plan trait for complex-to-complex transforms with 64-bit precision.

```APIDOC
### impl C2CPlan for Plan<c64, c64, Plan64>

#### Description

Implements the `C2CPlan` trait for `Plan<c64, c64, Plan64>`.

#### Type Alias: Complex

```rust
type Complex = Complex<f64>;
```

#### Function: new

```rust
fn new( shape: &[usize], in_: &mut [Self::Complex], out: &mut [Self::Complex], sign: Sign, flag: Flag, ) -> Result<Self>
```

##### Description

Create a new plan for complex-to-complex transform.

#### Function: c2c

```rust
fn c2c( &mut self, in_: &mut [Self::Complex], out: &mut [Self::Complex], ) -> Result<()>
```

##### Description

Execute the complex-to-complex transform using the created plan.

#### Function: aligned

```rust
fn aligned(shape: &[usize], sign: Sign, flag: Flag) -> Result<Self>
```

##### Description

Create a new plan with aligned vectors.
```

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

### Mutate exact-size chunks in reverse

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Uses rchunks_exact_mut to modify fixed-size chunks of a slice, starting from the end.

```rust
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.rchunks_exact_mut(2) {
    for elem in chunk.iter_mut() {
        *elem += count;
    }
    count += 1;
}
assert_eq!(v, &[0, 2, 2, 1, 1]);
```

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

### C2RPlan Implementation for Plan<c64, f64, Plan64>

Source: https://docs.rs/fftw/latest/fftw/plan/trait.C2RPlan.html

Concrete implementation of C2RPlan for double-precision floats (f64) and complex numbers (c64). Specifies Real as f64 and Complex as Complex<f64>.

```rust
impl C2RPlan for Plan<c64, f64, Plan64> {
    type Real = f64;
    type Complex = Complex<f64>;
}
```

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

### R2RPlan64::new

Source: https://docs.rs/fftw/latest/fftw/plan/type.R2RPlan64.html

Creates a new R2RPlan64 instance for performing real-to-real transforms.

```APIDOC
## R2RPlan64::new

### Description
Creates a new plan for real-to-real transforms with the specified shape, input/output buffers, transform kind, and flags.

### Parameters
- **shape** (&[usize]) - Required - The dimensions of the transform.
- **in_** (&mut [f64]) - Required - Mutable reference to the input buffer.
- **out** (&mut [f64]) - Required - Mutable reference to the output buffer.
- **kind** (R2RKind) - Required - The type of R2R transform to perform.
- **flag** (Flag) - Required - Configuration flags for the FFTW planner.

### Response
- **Result<Self>** - Returns a new R2RPlan64 instance or an error if the plan creation fails.
```

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

### Get mutable slice element or subslice

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Safely retrieves a mutable reference to an element or subslice by index or range.

```rust
let x = &mut [0, 1, 2];

if let Some(elem) = x.get_mut(1) {
    *elem = 42;
}
assert_eq!(x, &[0, 42, 2]);
```

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

### R2RPlan::aligned

Source: https://docs.rs/fftw/latest/fftw/plan/trait.R2RPlan.html

Creates a new plan with aligned memory allocation.

```APIDOC
## fn aligned

### Description
Creates a new plan with aligned vector allocation.

### Parameters
- **shape** (&[usize]) - Required - The dimensions of the transform.
- **kind** (R2RKind) - Required - The type of R2R transform.
- **flag** (Flag) - Required - FFTW planning flags.

### Response
- **Result<Self>** - Returns the new plan or an error.
```

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

### Get slice element or subslice

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Safely retrieves an element or subslice by index or range, returning None if out of bounds.

```rust
let v = [10, 40, 30];
assert_eq!(Some(&40), v.get(1));
assert_eq!(Some(&[10, 40][..]), v.get(0..2));
assert_eq!(None, v.get(3));
assert_eq!(None, v.get(0..4));
```

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

### rsplitn

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns an iterator over subslices separated by elements that match a predicate, limited to n items, starting from the end.

```APIDOC
## pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F>

### Description
Returns an iterator over subslices separated by elements that match `pred` limited to returning at most `n` items. This starts at the end of the slice and works backwards. The matched element is not contained in the subslices. The last element returned, if any, will contain the remainder of the slice.

### Parameters
- **n** (usize) - Required - The maximum number of items to return.
- **pred** (FnMut(&T) -> bool) - Required - The predicate function used to identify split points.
```

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

### R2RPlan64::r2r

Source: https://docs.rs/fftw/latest/fftw/plan/type.R2RPlan64.html

Executes the real-to-real transform using the configured plan.

```APIDOC
## R2RPlan64::r2r

### Description
Executes the real-to-real transform on the provided input and output buffers.

### Parameters
- **in_** (&mut [f64]) - Required - Mutable reference to the input buffer.
- **out** (&mut [f64]) - Required - Mutable reference to the output buffer.

### Response
- **Result<()>** - Returns Ok(()) on success, or an error if the execution fails.
```

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

### Reverse split a slice into at most N parts

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Splits a slice into subslices starting from the end, limited to at most n items.

```rust
let v = [10, 40, 30, 20, 60, 50];

for group in v.rsplitn(2, |num| *num % 3 == 0) {
    println!("{group:?}");
}
```

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

### R2RPlan::r2r

Source: https://docs.rs/fftw/latest/fftw/plan/trait.R2RPlan.html

Executes the real-to-real transform using the created plan.

```APIDOC
## fn r2r

### Description
Executes the real-to-real transform on the provided buffers.

### Parameters
- **in_** (&mut [Self::Real]) - Required - Input buffer.
- **out_** (&mut [Self::Real]) - Required - Output buffer.

### Response
- **Result<()>** - Returns Ok(()) on success or an error.
```

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

### C2RPlan::new

Source: https://docs.rs/fftw/latest/fftw/plan/trait.C2RPlan.html

Creates a new plan for a complex-to-real transformation.

```APIDOC
## fn new

### Description
Creates a new plan for a complex-to-real transformation.

### Parameters
- **shape** (&[usize]) - Required - The shape of the transformation.
- **in_** (&mut [Self::Complex]) - Required - Input buffer for complex data.
- **out** (&mut [Self::Real]) - Required - Output buffer for real data.
- **flag** (Flag) - Required - FFTW planning flags.

### Response
- **Result<Self>** - Returns the initialized plan or an error.
```

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

### Mutate slice chunks in reverse

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Uses rchunks_mut to modify elements within chunks of a slice, starting from the end.

```rust
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.rchunks_mut(2) {
    for elem in chunk.iter_mut() {
        *elem += count;
    }
    count += 1;
}
assert_eq!(v, &[3, 2, 2, 1, 1]);
```

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

### Get last chunk of slice

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns an array reference to the last N items in the slice, or None if the slice is too short.

```rust
let u = [10, 40, 30];
assert_eq!(Some(&[40, 30]), u.last_chunk::<2>());

let v: &[i32] = &[10];
assert_eq!(None, v.last_chunk::<2>());

let w: &[i32] = &[];
assert_eq!(Some(&[]), w.last_chunk::<0>());
```

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

### FFTW Plan Struct

Source: https://docs.rs/fftw/latest/fftw/plan/index.html

Documentation for the 'Plan' struct, which serves as a typed wrapper for `fftw_plan`.

```APIDOC
## Struct: Plan

### Description
Typed wrapper of `fftw_plan`.

### Fields
(No specific fields are detailed in the provided text.)

### Methods
(No specific methods are detailed in the provided text.)
```

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

### C2RPlan Implementation for Plan<c32, f32, Plan32>

Source: https://docs.rs/fftw/latest/fftw/plan/trait.C2RPlan.html

Concrete implementation of C2RPlan for single-precision floats (f32) and complex numbers (c32). Specifies Real as f32 and Complex as Complex<f32>.

```rust
impl C2RPlan for Plan<c32, f32, Plan32> {
    type Real = f32;
    type Complex = Complex<f32>;
}
```

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

### From Conversions

Source: https://docs.rs/fftw/latest/fftw/types/type.c64.html

Shows how to convert other types into Complex numbers.

```APIDOC
## From Conversions for Complex<T>

### Description
Implements conversions from other types into `Complex<T>`.

### Methods
- `from(re: &T) -> Complex<T>`: Converts from a reference to type `T`.
- `from(re: T) -> Complex<T>`: Converts from type `T`.

### Constraints
- `T: Clone + Num`
```

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

### rsplitn_mut

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns an iterator over mutable subslices separated by elements that match a predicate, limited to n items, starting from the end.

```APIDOC
## pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F>

### Description
Returns an iterator over mutable subslices separated by elements that match `pred` limited to returning at most `n` items. This starts at the end of the slice and works backwards. The matched element is not contained in the subslices. The last element returned, if any, will contain the remainder of the slice.

### Parameters
- **n** (usize) - Required - The maximum number of items to return.
- **pred** (FnMut(&T) -> bool) - Required - The predicate function used to identify split points.
```

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

### Partition Slice by Key

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

This nightly-only experimental API partitions a slice by moving consecutive elements that resolve to the same key to the end. It returns two slices: one with unique elements and one with duplicates.

```rust
#![feature(slice_partition_dedup)]

let mut slice = [10, 20, 21, 30, 30, 20, 11, 13];

let (dedup, duplicates) = slice.partition_dedup_by_key(|i| *i / 10);

assert_eq!(dedup, [10, 20, 30, 20, 11]);
assert_eq!(duplicates, [21, 30, 13]);

```

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

### Create New R2CPlan

Source: https://docs.rs/fftw/latest/fftw/plan/type.R2CPlan64.html

Creates a new real-to-complex plan. Requires specifying the shape of the transform, mutable slices for input real data and output complex data, and a planning flag. Returns a Result containing the plan or an error.

```rust
fn new( shape: &[usize], in_: &mut [Self::Real], out: &mut [Self::Complex], flag: Flag, ) -> Result<Self>
```

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

### pub fn rchunks_exact

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns an iterator over chunk_size elements of the slice at a time, starting at the end of the slice, omitting the remainder.

```APIDOC
## rchunks_exact

### Description
Returns an iterator over `chunk_size` elements of the slice at a time, starting at the end of the slice. If `chunk_size` does not divide the length of the slice, the remainder is omitted.

### Parameters
- **chunk_size** (usize) - Required - The number of elements per chunk. Panics if zero.
```

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

### Implement Plan Specification Traits

Source: https://docs.rs/fftw/latest/src/fftw/plan.rs.html

Macro to implement validation, destruction, and printing for FFTW plan types.

```rust
impl_plan_spec!(Plan64; fftw_destroy_plan, fftw_print_plan);
impl_plan_spec!(Plan32; fftwf_destroy_plan, fftwf_print_plan);
```

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

### Iterate over slice chunks in reverse

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Demonstrates using rchunks to iterate over a slice in chunks of a specified size, starting from the end.

```rust
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert_eq!(iter.next().unwrap(), &['l']);
assert!(iter.next().is_none());
```

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

### as_rchunks

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Splits a slice into `N`-element arrays starting from the end, and a remainder slice. The remainder contains the initial elements.

```APIDOC
## as_rchunks<const N: usize>

### Description
Splits the slice into a slice of `N`-element arrays, starting at the end of the slice, and a remainder slice with length strictly less than `N`.
The remainder is meaningful in the division sense. Given `let (remainder, chunks) = slice.as_rchunks()`, then:
  * `remainder.len()` equals `slice.len() % N`,
  * `chunks.len()` equals `slice.len() / N`, and
  * `slice.len()` equals `chunks.len() * N + remainder.len()`.

You can flatten the chunks back into a slice-of-`T` with `as_flattened`.

### Method
`fn as_rchunks(&self) -> (&[T], &[[T; N]])`

### Panics
Panics if `N` is zero.
Note that this check is against a const generic parameter, not a runtime value, and thus a particular monomorphization will either always panic or it will never panic.

### Examples
```rust
let slice = ['l', 'o', 'r', 'e', 'm'];
let (remainder, chunks) = slice.as_rchunks();
assert_eq!(remainder, &['l']);
assert_eq!(chunks, &[['o', 'r'], ['e', 'm']]);
```
```

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

### Implement R2R FFTW Plans

Source: https://docs.rs/fftw/latest/src/fftw/plan.rs.html

Macro to generate R2R plan implementations for specific floating-point types.

```rust
impl_r2r!(f64, Plan64; fftw_plan_r2r, fftw_execute_r2r);
impl_r2r!(f32, Plan32; fftwf_plan_r2r, fftwf_execute_r2r);
```

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

### Create New Complex-to-Complex Plan

Source: https://docs.rs/fftw/latest/fftw/plan/type.C2CPlan32.html

Creates a new plan for executing a complex-to-complex FFT. Requires mutable slices for input and output, along with sign, flag, and shape specifications.

```rust
fn new( shape: &[usize], in_: &mut [Self::Complex], out: &mut [Self::Complex], sign: Sign, flag: Flag, ) -> Result<Self>
```

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

### Create Aligned Complex-to-Complex Plan

Source: https://docs.rs/fftw/latest/fftw/plan/type.C2CPlan32.html

Creates a new plan for a complex-to-complex FFT with aligned vector support. This can improve performance on certain architectures. Requires shape, sign, and flag.

```rust
fn aligned(shape: &[usize], sign: Sign, flag: Flag) -> Result<Self>
```

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

### Mutably Iterate Over Slice Elements in Rust

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Use `iter_mut()` to get a mutable iterator over slice elements. This allows modification of each item.

```rust
let x = &mut [1, 2, 4];
for elem in x.iter_mut() {
    *elem += 2;
}
assert_eq!(x, &[3, 4, 6]);
```

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

### Get unchecked slice element

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Retrieves an element or subslice without bounds checking. Calling with an out-of-bounds index is undefined behavior.

```rust
let x = &[1, 2, 4];

unsafe {
    assert_eq!(x.get_unchecked(1), &2);
}
```

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

### Basic align_to Usage

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Demonstrates basic usage of `align_to` to split a byte slice into a prefix, a slice of `u16`, and a suffix. This method is unsafe and requires careful handling of memory alignment.

```rust
unsafe {
    let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
    let (prefix, shorts, suffix) = bytes.align_to::<u16>();
    // less_efficient_algorithm_for_bytes(prefix);
    // more_efficient_algorithm_for_aligned_shorts(shorts);
    // less_efficient_algorithm_for_bytes(suffix);
}
```

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

### Mutably reverse split a slice into at most N parts

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Splits a slice into mutable subslices starting from the end, limited to at most n items.

```rust
let mut s = [10, 40, 30, 20, 60, 50];

for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
    group[0] = 1;
}
assert_eq!(s, [1, 40, 30, 20, 60, 1]);
```

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

### C2CPlan Implementations

Source: https://docs.rs/fftw/latest/fftw/plan/trait.C2CPlan.html

Details on the implementations of the C2CPlan trait for different plan types.

```APIDOC
### Implementors

#### impl C2CPlan for Plan<c32, c32, Plan32>

##### type Complex = Complex<f32>

#### impl C2CPlan for Plan<c64, c64, Plan64>

##### type Complex = Complex<f64>
```

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

### pub fn rchunks_mut

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Returns an iterator over chunk_size elements of the slice at a time, starting at the end of the slice, providing mutable access.

```APIDOC
## rchunks_mut

### Description
Returns an iterator over `chunk_size` elements of the slice at a time, starting at the end of the slice. The chunks are mutable slices and do not overlap.

### Parameters
- **chunk_size** (usize) - Required - The number of elements per chunk. Panics if zero.
```

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

### C2RPlan aligned Method

Source: https://docs.rs/fftw/latest/fftw/plan/trait.C2RPlan.html

Provides a default implementation for creating a new plan with aligned vectors. Uses the shape and transformation flags.

```rust
fn aligned(shape: &[usize], flag: Flag) -> Result<Self> { ... }
```

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

### Slice Pointer Range Access

Source: https://docs.rs/fftw/latest/fftw/array/struct.AlignedVec.html

Get a half-open range of pointers spanning the slice. Useful for checking if a pointer belongs to the slice range.

```rust
let a = [1, 2, 3];
let x = &a[1] as *const _;
let y = &5 as *const _;

assert!(a.as_ptr_range().contains(&x));
assert!(!a.as_ptr_range().contains(&y));
```

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

### Create New R2R Plan

Source: https://docs.rs/fftw/latest/fftw/plan/type.R2RPlan64.html

Use this function to create a new real-to-real plan. Ensure input and output slices are mutable and correctly sized according to the shape.

```rust
fn new( shape: &[usize], in_: &mut [Self::Real], out: &mut [Self::Real], kind: R2RKind, flag: Flag, ) -> Result<Self>
```
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