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 minimum rank is 2. 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)