At Mon, 19 Jan 2009 18:20:56 -0500, Liam Healy wrote: > Is possible to change GSL to allow f & df _or_ fdf instead of "and", > say providing a null pointer for the unneeded function. If that's > already the case, can the documentation be made clear?
Hello, To keep things simple using a NULL pointer is not supported -- the recommended way is to make a small function fdf which calls f and df. > In a related puzzle, I find this statement about fdf hard to understand: > "This function provides an optimization of the separate functions for > f(x) and g(x)—it is always faster to compute the function and its > derivative at the same time. " > The user is providing the function, so whether it's an optimization or > not depends on how it's written. It seems like an overstatement that > it's "always" faster to compute the function and its derivative at the > same time; I'm willing to believe it's (essentially) at least as fast > perhaps. I was thinking that for analytic functions, at least, the function and the derivative always have some terms in common so it is faster to compute them together. -- Brian Gough _______________________________________________ Help-gsl mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-gsl
