MAT_VARCREATE(3)

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');
        } 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');
        } 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');
        } 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)