Plotting using octave within c++ and others..

[tarabas]

Hi all,

I am a new user (aka newbie) to the octace c++, meaning i just use the c++
library for my code.

I have a couple of questions. For someone experienced i can imagine this wud
be a piece of cake:-)

1) Is there a way to plot using octave calls from within c++ program e.g.
using feval..?? That wud be very handy:-)

a simple example:

#include <iostream>
#include <oct.h>
using namespace std;

int main(argc, argv)
{
  octave_main (argc, argv, 1);//this throws the octave message but can be
avoided
  ColumnVector x(2), y(2);
  x(0) =1; x(1)=2;
  y(0) =10; y(1)=20;
  octave_value_list f_arg, f_ret;
  f_arg(0) = octave_value(x);
  f_arg(1) = octave_value(y);
  f_ret=feval("plot",f_arg,1);
  if (!error_state )
  {
       cout << "ok" <<endl;
       double out = f_ret(0).double_value();
   }
  else
    std::cout << "error\n";
}

the above compiles and runs but no plot figure apperas. for other functions
like "rand" i get a proper result. 
actually i just managed to call functions within c++ using feval. 
Some comments here:
octave_main is needed otherwise i get a segmentation fault. this means that
the example in octave wiki compiles but doesn't run. can anyone give an
insight to this? i saw posts with people allocating symbol tables or
initiliazing symbol tables and others. in addition, the executable runs only
in the bin folder of octave (i use octave_gcc on windows xp). in any other
case i get message that "rand" or whatever feval function doesn't exist
despite the fact that i put all the necessary dll in the folder or add the
bin folder of octave in the system path. Strange isn't it?

2) If i define one ColumnVector and one RowVector, the rows() and columns()
member functions report same numbers. 

e.g.
    RowVector row(10);
    cout << row.rows() << " " << row.cols() << endl;
    ColumnVector col(10);
    cout << col.rows() << " " << col.cols() << endl;

it reports the same:
10 1
10 1

Isn't it a bug?? Shouldn' t the first one report "1 10"??

In this context what is the best way to insert new data in a Matrix in case
u dont know in advance the size of the matrix?


3) Are there any plans for writing proper documentation for octave c++
functions? I like the api (although a little bit limited e.g. Matrix type is
only double and only 2D).

Thank you for your time,

Regards,

tarabas

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