Some (probably) ridiculous questions

[Brian Gough]

Jean-Max Redonnet writes:
 > Sorry, if this point is obvious, but I'm not very familiar with GSL and I 
 > would like to use it in the right way.
 > 
 > My question is : How to declare a function of multiple variables ?
 > 
 > I manage with parametric curves and surfaces, so I need functions of one or 
 > two parameters. Futhermore This functions should be vectorial.
 > For example : I need to deal with a ruled surface.

Hello,

The gsl_function type is mainly designed for interfacing to the
univariate gsl routines.  It is not really a general facility so it
does not handle other cases that are not used in the library, such as
surfaces.

The way to handle this sort of situation is,

-- define your own surface function type in the way that you normally
would in your C-programs

-- if you need to use a gsl routine, for example to integrate along a
line, define a function to create the appropriate gsl_function by
mapping from your surface type.

Philosophically, calls to GSL routines, and the GSL types, can be at a
"lower-level" than your program.

regards
Brian Gough