Function setmathfuncs 

pub fn setmathfuncs(nam: &str, f: &mut [mathfunc], e: Option<&[i32]>) -> i32

Port of setmathfuncs() from Src/module.c:1374. — C decl setmathfuncs(char const *nam, MathFunc f, int size, int *e). Bulk add/delete of math-function definitions via the parallel e[] selector array (same shape as setconddefs).