External Interfaces Reference |
Set storage space for nonzero elements
Fortran Syntax
Arguments
pm
Pointer to a sparse mxArray
.
nzmax
The number of elements that mxCreateSparse
should allocate to hold the arrays pointed to by ir
, pr
, and pi
(if it exists). Set nzmax
greater than or equal to the number of nonzero elements in the mxArray
, but set it to be less than or equal to the number of rows times the number of columns. If you specify an nzmax
value of 0, mxSetNzmax
sets the value of nzmax
to 1.
Description
Use mxSetNzmax
to assign a new value to the nzmax
field of the specified sparse mxArray
. The nzmax
field holds the maximum possible number of nonzero elements in the sparse mxArray
.
The number of elements in the ir
, pr
, and pi
(if it exists) arrays must be equal to nzmax
. Therefore, after calling mxSetNzmax
, you must change the size of the ir
, pr
, and pi
arrays.
How big should nzmax
be? One thought is that you set nzmax
equal to or slightly greater than the number of nonzero elements in a sparse mxArray
. This approach conserves precious heap space. Another technique is to make nzmax
equal to the total number of elements in an mxArray
. This approach eliminates (or, at least reduces) expensive reallocations.
See Also
mxSetName (Obsolete) | mxSetPi |
© 1994-2005 The MathWorks, Inc.