MATLAB Central Newsreader - Sample Matlab Engine Doesn't Work?

Sample Matlab Engine Doesn't Work?

David Doria — Wed, 12 Mar 2008 21:39:05 -0400

I tried this in c++, but it produces a blank plot! I linked
to libmx.lib libmex.lib libeng.lib.

Seems very odd, it is clearly almost working because it is
producing a plot, but there is nothing on it!!
Any thoughts?

int main()
{
Engine *ep;

if (!(ep = engOpen("\0"))) {
fprintf(stderr, "\nCan't start MATLAB engine\n");
Pause();
return EXIT_FAILURE;
}
engEvalString(ep, "x = 1:1:10);");
engEvalString(ep, "y = x.^2;");
engEvalString(ep, "plot(x,y);");
engEvalString(ep, "title('Test');");
Pause();

//Free memory, close MATLAB engine.
engEvalString(ep, "close;");

Re: Sample Matlab Engine Doesn't Work?

James Tursa — Thu, 13 Mar 2008 06:37:18 -0400

On Wed, 12 Mar 2008 21:39:05 +0000 (UTC), "David Doria"
<daviddoria@gmail.com> wrote:

> engEvalString(ep, "x = 1:1:10);");

Typo, extra paren, this should be:

engEvalString(ep, "x = 1:1:10;");

The problem with using engEvalString is you don't get any feedback
that your string is invalid. There is a heavy burdon on the programmer
to examine the string carefully to make sure it is valid syntax, the
variables used are in existence, names are spelled correctly, etc.
etc. etc. It is good practice to copy & paste these strings into the
MATLAB workspace one by one to see that they do in fact work as
expected. This avoids wasting time trying to track down a non-existent
coding error in the C++ code itself.

James Tursa

Re: Sample Matlab Engine Doesn't Work?

David Doria — Thu, 13 Mar 2008 11:59:01 -0400

Oh man! Really sorry for the dumb mistake. I guess it's good
to know that is the case for the future when my commands are
more than 10 characters hahaha.

Thanks for the help.

David

James Tursa <aclassyguywithaknotac@hotmail.com> wrote in
message <64iht3dv5ou8htupbb01sr7t3majehnhju@4ax.com>...
> On Wed, 12 Mar 2008 21:39:05 +0000 (UTC), "David Doria"
> <daviddoria@gmail.com> wrote:
>
> > engEvalString(ep, "x = 1:1:10);");
>
> Typo, extra paren, this should be:
>
> engEvalString(ep, "x = 1:1:10;");
>
> The problem with using engEvalString is you don't get any
feedback
> that your string is invalid. There is a heavy burdon on
the programmer
> to examine the string carefully to make sure it is valid
syntax, the
> variables used are in existence, names are spelled
correctly, etc.
> etc. etc. It is good practice to copy & paste these
strings into the
> MATLAB workspace one by one to see that they do in fact
work as
> expected. This avoids wasting time trying to track down a
non-existent
> coding error in the C++ code itself.
>
> James Tursa