mxSetN (External Interfaces Reference)

Set number of columns in mxArray

C Syntax

#include "matrix.h"
void mxSetN(mxArray *array_ptr, int n);

Arguments

array_ptr
Pointer to an mxArray.

n
The desired number of columns.

Description

Call mxSetN to set the number of columns in the specified mxArray. The term "columns" always means the second dimension of a matrix. Calling mxSetN forces an mxArray to have two dimensions. For example, if array_ptr points to an mxArray having three dimensions, calling mxSetN reduces the mxArray to two dimensions.

You typically use mxSetN to change the shape of an existing mxArray. Note that mxSetN does not allocate or deallocate any space for the pr, pi, ir, or jc arrays. Consequently, if your calls to mxSetN and mxSetM increase the number of elements in the mxArray, then you must enlarge the pr, pi, ir, and/or jc arrays.

If your calls to mxSetM and mxSetN end up reducing the number of elements in the mxArray, then you may want to reduce the sizes of the pr, pi, ir, and/or jc arrays in order to use heap space more efficiently. However, reducing the size is not mandatory.

Examples

See mxsetdimensions.c in the mx subdirectory of the examples directory. For an additional example, see sincall.c in the refbook subdirectory of the examples directory.

See Also

mxGetM, mxGetN, mxSetM

mxSetM mxSetName (Obsolete)