For the multidimensional minimizer and root finder with derivatives there are three functions f, df, and fdf that are all presumably required. I can see that in some cases it would be advantageous to compute f and df together, but sometimes they are just as easily computed separately. In any case, either f and df, or fdf would be provided. However, the manual doesn't really say, but implies, that all three must be provided (at least the examples provide all three). 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?
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. Thanks, Liam _______________________________________________ Help-gsl mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-gsl
