### Start Grace with Named Pipe

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/Tutorial.html

Starts the xmgrace application and directs its input and output through a named pipe. This allows for external control of Grace by sending commands and data to the specified pipe.

```bash
mkfifo pvc
xmgrac`e` `_-_npipe``p``_v_c`&
```

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

### xmgrace Command Interpreter - Pattern Selections

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Details how to select patterns using the PATTERN expression, specifying the required ID type and providing an example.

```text
PATTERN _id_: pattern with ID _id_
nexpr _id_
PATTERN 1
```

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

### xmgrace Command Interpreter - Graph Selections

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Explains how to select sets within a graph using expressions like _graph_.SETS[_id_] and _graph_.S_nn_, specifying the types and examples for each selection method.

```text
_graph_.SETS[_id_]: set _id_ in graph _graph_
indx _id_, graphsel _graph_
GRAPH[0].SETS[1]

_graph_.S_nn_: set _nn_ in graph _graph_
_nn_: 0-99, graphsel _graph_
G0.S1
```

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

### Compile and Load Custom C Function for Grace

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

This example demonstrates how to define a custom function in C, compile it into a shared library, and then load it into Grace. The C code defines `my_function` which takes an integer and a double, returning their product. Compilation involves creating a Position Independent Code (PIC) object file and then a shared library.

```c
double my_function (int n, double x) {
    double retval;
    retval = (double) n * x;
    return (retval);
}
```

```bash
$gcc -c -fPIC my_func.c
$gcc -shared my_func.o -o /tmp/my_func.so
$strip /tmp/my_func.so
```

```grace
USE "my_function" TYPE f_of_nd FROM "/tmp/my_func.so" ALIAS "myf"
```

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

### Grace USE Statement for OS/2 DLL

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Examples of how to use a custom DLL function within Grace. It shows two methods: placing the DLL in the LIBPATH for a short form or specifying the full path to the DLL.

```grace
USE "my_function" TYPE f_of_nd FROM "my_func" ALIAS "myf"
```

```grace
USE "my_function" TYPE f_of_nd FROM "e:/foo/my_func.dll" ALIAS "myf"
```

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

### xmgrace Command Interpreter - Color Selections

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Explains the selection of mapped colors using COLOR expressions, differentiating between named colors and colors specified by an ID, with examples for each.

```text
COLOR _"colorname"_: a mapped color _colorname_
-
COLOR "red"

COLOR _id_: a mapped color with ID _id_
nexpr _id_
COLOR 2
```

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

### Grace Typesetting Control Codes Example

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

An example demonstrating the use of Grace's typesetting control codes to format a string, including subscripts, superscripts, font changes, and special character insertion.

```grace
F\sX\N(\xe\f{}) = sin(\xe\f{})\#{b7}e\S-X\N\#{b7}cos(\xe\f{})
```

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

### Real-time Plotting with grace_np

Source: https://context7.com/fxcoudert/xmgrace/llms.txt

Demonstrates how to initialize a Grace subprocess, register a custom error handler, and stream data points for real-time visualization. The example includes periodic display updates using GraceFlush and a manual wait mechanism.

```c
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "grace_np.h"

/* Custom error handler */
void my_error_function(const char *msg) {
    fprintf(stderr, "Grace Error: %s\n", msg);
}

int main(int argc, char *argv[]) {
    int i;
    double x, y;

    /* Register custom error handler */
    GraceRegisterErrorFunction(my_error_function);

    /* Open Grace with 2048 byte buffer */
    if (GraceOpen(2048) == -1) {
        fprintf(stderr, "Can't open Grace\n");
        exit(EXIT_FAILURE);
    }

    /* Send initialization commands */
    GracePrintf("world 0, -1, 100, 1");
    GracePrintf("xaxis tick major 20");
    GracePrintf("yaxis tick major 0.5");
    GracePrintf("s0 line color 2");
    GracePrintf("s0 symbol 1");
    GracePrintf("s0 symbol size 0.3");

    /* Plot data points in real-time */
    for (i = 0; i <= 100; i++) {
        x = (double) i;
        y = sin(x * 3.14159 / 50.0);

        /* Add point to set */
        GracePrintf("g0.s0 point %g, %g", x, y);

        /* Update display every 10 points */
        if (i % 10 == 0) {
            GracePrintf("redraw");
            GraceFlush();
            usleep(100000);  /* 100ms delay */
        }
    }

    /* Final update */
    GracePrintf("autoscale");
    GracePrintf("redraw");
    GraceFlush();

    /* Wait for user to close Grace */
    printf("Press Enter to close Grace...\n");
    getchar();

    /* Close the Grace subprocess */
    GraceClose();

    return 0;
}
```

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

### Customize File Dialog Patterns in X Resources

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

This snippet illustrates how to alter the default filename patterns for file selection dialogs in XMGrace. It provides an example for changing the pattern in the 'Open project' dialog to display all files.

```X Resources
XMgrace*openProjectFSB.pattern: *
```

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

### Control XMGrace via C API

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Demonstrates initializing a Grace session, sending plotting commands, and streaming data points to the application. Requires the grace_np library and proper linking during compilation.

```c
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <grace_np.h>

#ifndef EXIT_SUCCESS
#  define EXIT_SUCCESS 0
#endif
#ifndef EXIT_FAILURE
#  define EXIT_FAILURE -1
#endif

void my_error_function(const char *msg) {
    fprintf(stderr, "library message: \"%s\"\n", msg);
}

int main(int argc, char* argv[]) {
    int i;
    GraceRegisterErrorFunction(my_error_function);

    if (GraceOpen(2048) == -1) {
        fprintf(stderr, "Can't run Grace. \n");
        exit(EXIT_FAILURE);
    }

    GracePrintf("world xmax 100");
    GracePrintf("world ymax 10000");
    GracePrintf("s0 on");
    
    for (i = 1; i <= 100 && GraceIsOpen(); i++) {
        GracePrintf("g0.s0 point %d, %d", i, i);
        GracePrintf("g0.s1 point %d, %d", i, i * i);
        if (i % 10 == 0) {
            GracePrintf("redraw");
            sleep(1);
        }
    }

    if (GraceIsOpen()) {
        GracePrintf("saveall \"sample.agr\"");
        GraceClose();
        exit(EXIT_SUCCESS);
    } else {
        exit(EXIT_FAILURE);
    }
}
```

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

### Initialize and Control Grace Subprocess

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Demonstrates the lifecycle of a Grace subprocess, including opening a connection, sending commands, and closing the pipe. The C interface supports formatted strings, while Fortran requires manual command formatting.

```c
#include "grace_np.h"

int main() {
    if (GraceOpen(2048) == 0) {
        GracePrintf("g0.s0 point %f, %f\n", 3.5, 4.2);
        GracePrintf("redraw\n");
        GraceClose();
    }
    return 0;
}
```

```fortran
integer status
status = GraceOpenF(2048)
if (status .eq. 0) then
    call GraceCommandF("g0.s0 point 3.5, 4.2")
    call GraceCommandF("redraw")
    call GraceCloseF()
endif
```

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

### OS/2 DLL Creation with GCC

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Steps to compile C source code into an object file, create a linker definition file, and link them to create a DLL on OS/2 using GCC and EMX. This process involves specific compiler and linker flags for DLL creation and export.

```bash
gcc -Zomf -Zmt -c my_func.c -o my_func.obj
```

```bash
gcc my_func.obj my_func.def -o my_func.dll -Zdll -Zno-rte -Zmt -Zomf
```

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

### xmgrace Command Interpreter - Region Selections

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Describes how to select regions within a graph using the R_n_ expression, specifying the range for 'n' and providing an example.

```text
R_n_: region _n_
_n_: 0-4
R0
```

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

### Define Non-linear Fitting Function

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/Tutorial.html

Example syntax for defining a custom non-linear function within the XMGrace non-linear fitting widget using parameters a0 through a9.

```Grace
y = a0*sqrt(x) + a1*exp(x) + a2
```

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

### OS/2 DLL Linker Definition File

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

A sample linker definition file ('my_func.def') for creating an OS/2 DLL. It specifies library information, load settings for code and data, a description, and lists the exported functions.

```linker_script
* * *           LIBRARY my_func INITINSTANCE TERMINSTANCE          CODE LOADONCALL          DATA LOADONCALL MULTIPLE NONSHARED          DESCRIPTION 'This is a test DLL: my_func.dll'          EXPORTS          my_function            * * *
```

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

### xmgrace Command Interpreter - Set Selections

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Illustrates methods for selecting sets in the current graph, including SET[_id_], S_nn_, S_, and S$, detailing their respective expression types and usage.

```text
SET[_id_]: set _id_ in the current graph
indx _id_
SET[1]

S_nn_: set _nn_ in the current graph
_nn_: 0-99
S1

S_: the last implicitly (i.e. as a result of a data transformation) allocated set in the current graph
-
S_

S$: the active set in the current graph
-
S$
```

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

### xmgrace Command Interpreter - Expression Types

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Defines various expression types used in the xmgrace command interpreter, including numeric, integer, non-negative integer, string, and vector expressions, along with their characteristics and examples.

```text
expr: Any numeric expression
1.5 + sin(2)

iexpr: Any expression that evaluates to an integer
25, 0.1 + 1.9, PI/asin(1)

nexpr: Non-negative iexpr
2 - 1

indx: Non-negative iexpr

sexpr: String expression
"a string", "a " . "string", "square root of 4 = " . sqrt(4)

vexpr: Vector expression
"2*x"
```

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

### Automate Plotting with XMGrace Batch Commands

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/Tutorial.html

This snippet demonstrates how to create a batch command file to modify plot aesthetics and labels, followed by the command-line execution syntax for XMGrace.

```Grace
#Obligatory descriptive comment
s0.y = s0.y * 1000
s0 line color 3
s1 line color 4
title "A Gnasty Graph"
xaxis label "Time ( s )"
yaxis label "Gnats ( 1000's  )"
autoscale
```

```bash
xmgrace foo.dat bar.dat -batch bfile
```

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

### Customize Menu Accelerators in X Resources

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

This snippet demonstrates how to assign keyboard accelerators to menu items in XMGrace by modifying the .Xresources file. It shows the resource names derived from menu labels and their corresponding accelerator key combinations.

```X Resources
XMgrace*transformationsMenu.nonLinearCurveFittingButton.acceleratorText: Ctrl+F
XMgrace*transformationsMenu.nonLinearCurveFittingButton.accelerator: Ctrl<Key>f
```

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

### Grace Batch Processing Script

Source: https://context7.com/fxcoudert/xmgrace/llms.txt

A configuration file for Grace's batch mode, used for automated data processing and export. It handles page setup, file I/O, baseline shifting, and smoothing.

```text
# batch_example.bat - Grace batch script
# Run with: gracebat -batch batch_example.bat -nosafe -hardcopy

# Page setup for publication quality
page size 595 842
hardcopy device "EPS"
device "EPS" op "level2"

# Read input data
cd "/path/to/data"
read "experiment.dat"

# Data preprocessing - shift baseline
s0.y = s0.y - AVG(s0.y[0:10])

# Apply smoothing
RUNAVG(s0, 5)

# Create fitted curve in s1
s1 length 100
s1.x = mesh(MIN(s0.x), MAX(s0.x), 100)
```

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

### Configure XMGrace Axis and Viewport

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Commands to define world coordinate ranges, viewport boundaries, axis scaling modes, and inversion settings.

```XMGrace
WORLD XMIN -10
WORLD YMAX 1e4
VIEW XMIN .2
VIEW 0.15, 0.15, 1.15, 0.85
XAXES SCALE LOGARITHMIC
YAXES INVERT OFF
AUTOSCALE ONREAD NONE
```

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

### Manipulate Data Points in XYDYDY Sets in xmgrace

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/FAQ.html

This example shows how to assign values to individual data points within an XYDYDY set when the 'POINT' command does not directly support multiple Y-values. It involves accessing and modifying specific elements of the Y-arrays.

```xmgrace batch
S0 POINT expr, expr
S0.Y1[S0.LENGTH - 1] = expr
S0.Y2[S0.LENGTH - 1] = expr
...
```

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

### xmgrace Command Interpreter - Arithmetic Operators

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Lists the supported arithmetic operators in the xmgrace command interpreter, including addition, subtraction, multiplication, division, modulus, and exponentiation.

```text
Operator | Description
+ | addition
- | substraction
* | multiplication
/ | division
% | modulus
^ | raising to power
```

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

### Specify Xmgr Version for File Compatibility

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/FAQ.html

When dealing with older Xmgr project files, inserting a version line at the beginning can ensure compatibility. The format `@VERSION versionid` specifies the Xmgr version the file was created with. For example, `@VERSION 40102` corresponds to version 4.1.2.

```text
@VERSION 40102
```

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

### Evaluate Expression: Combining Data Sets

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Illustrates creating a new data set by combining coordinates from multiple existing sets using a mathematical formula. This example uses the y-coordinate from the source set, a sine function of the x-coordinate, and the y-coordinate from a second set (s2.y). It assumes all sets have the same number of points.

```grace
y = y - 0.653 * sin (x deg) + s2.y
```

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

### Perform Data Transformations in XMGrace

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

Demonstrates how to manipulate data sets directly using the XMGrace command interpreter. These operations allow for scaling, running statistics, and interpolation on data sets.

```XMGrace Command
S1.X = S1.X * 0.000256
RUNAVG(S0, 100)
RUNMED(S0, 100)
INTERPOLATE(S0, S1.X, ASPLINE, OFF)
HISTOGRAM(S0, MESH(0, 1, 11), OFF, ON)
INTEGRATE(S0)
```

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

### Feature Extraction: Y Maximum in XMGrace

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/Tutorial.html

Extracts a specific feature (e.g., Y maximum) from a family of curves to create a new data set. The x-values of the new data set can be derived from the set number, original x or y values, or the legend entry of the source curves. This example demonstrates extracting the Y maximum and using the set index for the x-values.

```xmgrace commands
# Example command sequence for Y maximum extraction (conceptual)
# Assuming GUI actions are translated to commands or script
# Set source graph and feature
# Set x-value source to 'index'
# Apply transformation
```

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

### Arranging Graphs in a Matrix in XMGrace

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

The ARRANGE command organizes existing graphs into a matrix format with specified rows, columns, and spacing. It supports various parameters to control the layout, including offsets, horizontal and vertical gaps, and flags for altering fill order and snake-like filling.

```xmgrace
ARRANGE(2, 2, 0.1, 0.15, 0.2)
```

```xmgrace
ARRANGE(2, 2, 0.1, 0.15, 0.2, ON, OFF, ON)
```

```xmgrace
ARRANGE(2, 2, 0.1, 0.15, 0.2, ON, OFF, ON, ON)
```

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

### Registering Fortran Function in xmgrace

Source: https://github.com/fxcoudert/xmgrace/blob/master/doc/UsersGuide.html

This command informs xmgrace about the newly created Fortran function. It uses the 'USE' command to load the shared library and define the function's type, source, and an alias for use within xmgrace.

```grace
USE "myfunc_wrapper" TYPE f_of_nd FROM "/tmp/myfunc.so" ALIAS "myfunc"
```