
266 Introduction to Computational Modeling
int gsl deriv forward (const gsl function
*
ufunc,
double x, double h, double
*
result, double
*
abserr)
This function computes the derivative of the function ufunc at the point x us-
ing an adaptive forward difference algorithm with a step-size of h. The func-
tion is evaluated only at points greater than x. The derivative is returned by
the function and an estimate of its absolute error is returned in abserr. This
function should be used if ufunc has a discontinuity at x, or is undefined for
values less than x.
int gsl deriv backward (const gsl function
*
ufunc,
double x, double h, double
*
result, double
*
abserr)
This ...