User`s manual

3 Creating Fortran MEX-Files

3-28

For an input 2-by-3 matrix

x = [1 2 3; 4 5 6];

typing

y = dblmat(x)

yields

y =

2 4 6

8 10 12

Note The dblmat.f example, as well as fulltosparse.f and sincall.f, are

split into two parts, the gateway and the computational subroutine, because of

restrictions in some compilers.

Handling Sparse Matrices

The MATLAB API provides a set of functions that allow you to create and

manipulate sparse matrices from within your MEX-files. There are special

parameters associated with sparse matrices, namely

ir, jc, and nzmax. For

information on how to use these parameters and how MATLAB stores sparse

matrices in general, refer to the section on “The MATLAB Array” on page 1-6.

Note Sparse array indexing is zero-based, not one-based.

This example illustrates how to populate a sparse matrix.

C $Revision: 1.6 $

C===============================================================

C fulltosparse.f

C Example for illustrating how to populate a sparse matrix.

C For the purpose of this example, you must pass in a

C non-sparse 2-dimensional argument of type real double.