info ginac

6.3.2 Print methods for functions

Symbolic functions employ a print method dispatch mechanism similar to the one used for classes. The methods are specified with print_func<C>() function options. If you don't specify any special print methods, the function will be printed with its name (or LaTeX name, if supplied), followed by a comma-separated list of arguments enclosed in parentheses.

For example, this is what GiNaC's ‘abs()’ function is defined like:

static ex abs_eval(const ex & arg) { ... }
static ex abs_evalf(const ex & arg) { ... }
                                                                                
static void abs_print_latex(const ex & arg, const print_context & c)
{
    c.s << "{|"; arg.print(c); c.s << "|}";
}
                                                                                
static void abs_print_csrc_float(const ex & arg, const print_context & c)
{
    c.s << "fabs("; arg.print(c); c.s << ")";
}
                                                                                
REGISTER_FUNCTION(abs, eval_func(abs_eval).
                       evalf_func(abs_evalf).
                       print_func<print_latex>(abs_print_latex).
                       print_func<print_csrc_float>(abs_print_csrc_float).
                       print_func<print_csrc_double>(abs_print_csrc_float));

This will display ‘abs(x)’ as ‘|x|’ in LaTeX mode and fabs(x) in non-CLN C source output, but as abs(x) in all other formats.

There is currently no equivalent of set_print_func() for functions.