Hi, when you declare a new function on GiNaC you has to declare it with DECLARE_FUNCTION_xP (where x is the number of parameters), there is no DECLARE_FUNCTION_0P, and basically, there is no need for it (i think :), you won't derivate that function, or expand it, so, you don't need that support to a function of 0 args ). Why don't you declare it like a normal function? #include <iostream> #include <ginac/ginac.h> using namespace std; using namespace GiNaC; ex myfcn(void) { symbol a("a"), b("b"), c("c"); GiNaC::matrix D(2,2), E(2,2); D = a, b, 0, c; E = sin(a), cos(b), -sin(c), cos(a); return D.mul(E); } int main(void) { ex r = myfcn(); cout << r << endl; } /tmp$ g++ -lginac -o test test.cpp /tmp$ ./test [[-sin(c)*b+a*sin(a),cos(a)*b+a*cos(b)],[-c*sin(c),c*cos(a)]] I hope that you find this useful. Bye. 2009/7/27 Michael Hoffmann <michael.hoffmann@unibw.de>:

Hallo, how can I make a function without any arguments with GiNaC? I just need a function returned a symbolic matrix. It's the same matrix every time. How I have to declare  such a function?

minimal example:

#include <stdio.h> #include <stdlib.h> #include <iostream> #include <math.h> #include <ginac/ginac.h> using namespace std; using namespace GiNaC;

REGISTER_FUNCTION (symbolic_matrix, dummy()); {            symbol a("a"), b("b"), c("c");

           GiNaC::matrix D(2,2), E(2,2);

           D = a, b,                  0, c;

           E = sin(a), cos(b),                 -sin(c), cos(a);

           GiNaC::ex h = D.mul(E) ;

           return h;        }

Thank you very match, Michael Hoffmann

P.S. : sorry for my english!

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