NAME¶

Mat_VarCreate — Creates a MAT variable structure.

SYNOPSIS¶

#include <matio.h>

matvar_t *
Mat_VarCreate(const char *name, enum matio_classes class_type, enum matio_types data_type, int rank, const size_t *dims, const void *data, int opt);

DESCRIPTION¶

The Mat_VarCreate() function creates a MAT structure variable named name that can be written to a MAT file. The class_type argument specifies the class of the variable, and the data_type argument specifies the type of the data. For example, a double-precision class would use MAT_C_DOUBLE for the class type and MAT_T_DOUBLE for the data type. In some instances, the data type may not match the class type. For example, an array of integers can be written in the double-precision class by using MAT_T_INT32 for data_type.

The rank argument specifies how many dimensions the data has. The number of elements in each dimension is specified in the array dims.

The data argument is a pointer to the variable data. The pointer is typically a pointer to a numeric array (e.g. double, float, int, etc.) for real variables. For complex variables, the pointer is a pointer to a mat_complex_split_t which contains pointers to the real and imaginary data as fields of the structure. For sparse variables, the pointer should be a mat_sparse_t *.

RETURN VALUES¶

If the variable was successfully created, a pointer to the variable is returned. Otherwise NULL is returned. The variable should be free'd when no longer needed using Mat_VarFree().

EXAMPLES¶

The example program below creates a MAT file named test.mat, and writes two real numeric variables x and y and a complex variable z to the file.

#include <stdlib.h>
#include <stdio.h>
#include "matio.h"

int
main(int argc,char **argv)
{
    mat_t    *matfp;
    matvar_t *matvar;
    size_t    dims[2] = {10,1};
    double    x[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9,10},
              y[10] = {11,12,13,14,15,16,17,18,19,20};
    struct mat_complex_split_t z = {x, y};

    matfp = Mat_CreateVer("test.mat", NULL, MAT_FT_DEFAULT);
    if ( NULL == matfp ) {
        fprintf(stderr, "Error creating MAT file
        return EXIT_FAILURE;
    }

    matvar = Mat_VarCreate("x", MAT_C_DOUBLE, MAT_T_DOUBLE, 2, dims, x, 0);
    if ( NULL == matvar ) {
        fprintf(stderr, "Error creating variable for 'x'0);
    } else {
        Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_NONE);
        Mat_VarFree(matvar);
    }

    matvar = Mat_VarCreate("y", MAT_C_DOUBLE, MAT_T_DOUBLE, 2, dims, y, 0);
    if ( NULL == matvar ) {
        fprintf(stderr, "Error creating variable for 'y'0);
    } else {
        Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_NONE);
        Mat_VarFree(matvar);
    }

    matvar = Mat_VarCreate("z", MAT_C_DOUBLE, MAT_T_DOUBLE, 2, dims, &z,
                 MAT_F_COMPLEX);
    if ( NULL == matvar ) {
        fprintf(stderr, "Error creating variable for 'z'0);
    } else {
        Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_NONE);
        Mat_VarFree(matvar);
    }

    Mat_Close(matfp);
    return EXIT_SUCCESS;
}

SEE ALSO¶

Mat_VarCreateStruct(3), Mat_VarFree(3), Mat_VarWrite(3)