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

[Chidambaram Annamalai]

Oops. I didn't even bother to check the Octave C++ API reference for
save_binary_data! I found that the last argument controls the storage
precision.

OCTINTERP_API bool save_binary_data     (       std::ostream &          os,
                const octave_value &    tc,
                const std::string &     name,
                const std::string &     doc,
                bool    mark_as_global,
                bool    save_as_floats  
        )                       

Chillu

On 6/7/10, Chidambaram Annamalai <address@hidden> wrote:
> Thanks a lot! This is what I wanted to achieve.
>
> Could you also tell me how I could modify the save_binary_data
> function arguments so that the Matrix A is stored in single precision
> in the binary file? I believe real matrices in octave are by default
> in double precision. I tried float_value (A) but it didn't work.
>
> Thanks,
> Chillu
>
> On 6/7/10, Carlo de Falco <address@hidden> wrote:
>>
>> 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.
>>
>