User`s manual

3 Creating Fortran MEX-Files

3-10

A First Example — Passing a Scalar

Let’s look at a simple example of Fortran code and its MEX-file equivalent.

Here is a Fortran computational routine that takes a scalar and doubles it.

subroutine timestwo(y, x)

real*8 x, y

y = 2.0 * x

return

end

Below is the same function written in the MEX-file format.

C--------------------------------------------------------------

C timestwo.f

C Multiply the input argument by 2.

C This is a MEX-file for MATLAB.

C $Revision: 1.11 $

subroutine mexFunction(nlhs, plhs, nrhs, prhs)

C--------------------------------------------------------------

C (pointer) Replace integer by integer*8 on the DEC Alpha

C platform.

integer plhs(*), prhs(*)

integer mxGetPr, mxCreateFull

integer x_pr, y_pr

C--------------------------------------------------------------

integer nlhs, nrhs

integer mxGetM, mxGetN, mxIsNumeric

integer m, n, size

real*8 x, y