## Evaluation of interpolating functions

Function: double gsl_interp_eval (const gsl_interp * interp, const double xa[], const double ya[], double x, gsl_interp_accel * a)
Function: int gsl_interp_eval_e (const gsl_interp * interp, const double xa[], const double ya[], double x, gsl_interp_accel * a, double * y)
These functions return the interpolated value of y for a given point x, using the interpolation object interp, data arrays xa and ya and the accelerator a.

Function: double gsl_interp_eval_deriv (const gsl_interp * interp, const double xa[], const double ya[], double x, gsl_interp_accel * a)
Function: int gsl_interp_eval_deriv_e (const gsl_interp * interp, const double xa[], const double ya[], double x, gsl_interp_accel * a, double * d)
These functions return the derivative d of an interpolated function for a given point x, using the interpolation object interp, data arrays xa and ya and the accelerator a.

Function: double gsl_interp_eval_deriv2 (const gsl_interp * interp, const double xa[], const double ya[], double x, gsl_interp_accel * a)
Function: int gsl_interp_eval_deriv2_e (const gsl_interp * interp, const double xa[], const double ya[], double x, gsl_interp_accel * a, double * d2)
These functions return the second derivative d2 of an interpolated function for a given point x, using the interpolation object interp, data arrays xa and ya and the accelerator a.

Function: double gsl_interp_eval_integ (const gsl_interp * interp, const double xa[], const double ya[], double a, double bdouble x, gsl_interp_accel * a)
Function: int gsl_interp_eval_integ_e (const gsl_interp * interp, const double xa[], const double ya[], , double a, double b, gsl_interp_accel * a, double * result)
These functions return the numerical integral result of an interpolated function over the range [a, b], using the interpolation object interp, data arrays xa and ya and the accelerator a.