Re: Octave from C++: Saving objects in binary

[Carlo de Falco]

On 7 Jun 2010, at 07:27, Chidambaram Annamalai wrote:

> I need to create large random matrices and perform computations with
> them, finally saving the results to a file.
>
> I had no trouble in creating the matrices in C++ after including the
> necessary octave headers like so:
>
>    octave_rand gauss;
>    gauss.normal_distribution();
>    std::cout << "Creating gaussian random matrix... ";
>    Matrix A = gauss.matrix(M, N);
>
> However, supposing I want to save this matrix A to a file how do I go
> about doing that?
>
> I tried the "feval" method provided here:
> http://wiki.octave.org/wiki.pl?CategoryExternal but there's a problem.
> The "save" function that I'm interested in, will only take string
> arguments and when I supply it with the argument "A" to save to a
> binary file it shows the error:
>
> warning: save: no such variable `A'
>
> Now how do I tell the "save" function to take the matrix A then? The
> problem seems to be that the variable A is not being created in the
> memory that is being seen by "save". How do I do that?
>
> Thanks,
> Chillu

I'm not sure using feval is the simplest approach,
you could use

#include <octave/load-save.h>
#include <octave/ls-oct-binary.h>
 std::ofstream os ("A.mat");
 bool boolvar(false);
 write_header (os, LS_BINARY);
 save_binary_data (os, octave_value (A),
                   std::string("A"), std::string(""),
                   boolvar, boolvar);
 os.close();

instead.
HTH,
c.