.\" Copyright (c) 2015-2026, The matio contributors

.\" Copyright (c) 2012-2014, Christopher C. Hulbert

.\" All rights reserved.

.\"

.\" SPDX-License-Identifier: BSD-2-Clause

.\"

.Dd September 12, 2019

.Dt MAT_VARWRITE 3

.Os

.Sh NAME

.Nm Mat_VarWrite

.Nd Writes a MATLAB variable to a MATLAB MAT file.

.Sh SYNOPSIS

.Fd #include <matio.h>

.Ft int

.Fo Mat_VarWrite

.Fa "mat_t *matfp"

.Fa "matvar_t *matvar"

.Fa "enum matio_compression compress"

.Fc

.Sh DESCRIPTION

The

.Fn Mat_VarWrite

function writes the MATLAB variable

.Fa matvar

to the MAT file

.Fa matfp

which must be opened for writing. If the MAT file is a version 5 or HDF5 MAT

file, the

.Fa compress

option allows the variable to be written using zlib compression if available.

If compression is not available, the variable is written uncompressed.

.Sh RETURN VALUES

The function returns 0 if the variable was successfully written to the MAT file.

Otherwise, an error value is returned.

.Sh EXAMPLES

This example program creates a MAT file named by the first argument to the

program, and writes the variable named

.Em m_pi

to the file.

.Bd -literal

#include <math.h>

#include "matio.h"

int

main(int argc, char **argv)

{

mat_t *matfp;

matvar_t *matvar;

size_t dims[2] = {1, 1};

double m_pi = M_PI;

matfp = Mat_CreateVer(argv[1], NULL, MAT_FT_DEFAULT);

if ( NULL == matfp ) {

fprintf(stderr, "Error creating MAT file %s\n", argv[1]);

return EXIT_FAILURE;

}

matvar = Mat_VarCreate("m_pi", MAT_C_DOUBLE, MAT_T_DOUBLE,

2, dims, &m_pi, 0);

if ( NULL != matvar ) {

Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB);

Mat_VarFree(matvar);

}

Mat_Close(matfp);

return EXIT_SUCCESS;

}

.Ed

.Sh SEE ALSO

.Xr Mat_CreateVer 3 ,

.Xr Mat_Open 3 ,

.Xr Mat_VarRead 3 ,

.Xr Mat_VarWriteAppend 3