Re: Better quadrature routine in octave

[Pedro Gonnet]

On Sun, 2010-04-25 at 20:38 +0200, David Bateman wrote:

> Why not use the make_fcn_handle function from ov-fcn-handle.cc to create 
> an anonymous function using the string above with "f" replaced with the 
> string given by the fcn_name method of the ov-fcn-handle class or the 
> the arg itself if a string is passed to your quadrature function?
> 
> D.

Ok, thanks, that seems to work... Except that if I store the integrand
"f" as 

        octave_function *fcn = arg(0).function_value();
        
and then try to access its name using

        fcn->name()
        
I get an empty string for anonymous functions... Am I doing something
wrong here? The complete code is

          if ( std::isinf(a) || std::isinf(b) ) {
            std::string fstr = "(x) ";
            fstr.append(fcn->name());
            fstr.append("( tan ( pi / 2 * x ) ) .* ( 1 + tan ( pi * x / 2 ).^2 
) * pi / 2; endfunction;");
            fcn = make_fcn_handle(fstr).function_value();
            for ( i = 0 ; i <= nivals ; i++ )
                if ( std::isinf(iivals[i]) )
                    iivals[i] = copysign(1.0,iivals[i]);
                else
                    iivals[i] = 2.0 * atan(iivals[i]) / M_PI;
            } 

Cheers and thanks again,
Pedro