The Explicit Structure

 

Explicit only adds three pointers to coordinate functions and information about the time-dependent domain of the surface to its superclass.  

#CLASS Explicit : Surface {
  DOMAIN_PARM *domain_parm;  /* Domain parameter for surface (see below) */
  COMPLEX (*compute_arg)();  /* Function pointer for user
                                supplied compute function */
  struct {
    t_fun *x, *y, *z;        /* Explicit coordinate functions  */
  } coord_f;
};

The data for domain_parm and coord_f are usually read from a description file with extension *.ex (see 8.2.5.1), the functions are read as strings, compiled into a t_fun with the function compiler and evaluated during the computation (refer to section 10.2.8 for a description of the function compiler). The time_parm variables can be used for the functions, see section 8.2.2.1.

The compute_arg function can be used to transform the rectangular default domain, see section 8.2.5.2 for an example.