### 28.13 2D Evaluation of Interpolating Functions

Function: double gsl_interp2d_eval (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc)
Function: int gsl_interp2d_eval_e (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc, double * z)

  These functions return the interpolated value of z for a given point (x,y), using the interpolation object interp, data arrays xa, ya, and za and the accelerators xacc and yacc. When x is outside the range of xa or y is outside the range of ya, the error code `GSL_EDOM` is returned.

Function: double gsl_interp2d_eval_extrap (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc)
Function: int gsl_interp2d_eval_extrap_e (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc, double * z)

  These functions return the interpolated value of z for a given point (x,y), using the interpolation object interp, data arrays xa, ya, and za and the accelerators xacc and yacc. The functions perform no bounds checking, so when x is outside the range of xa or y is outside the range of ya, extrapolation is performed.

Function: double gsl_interp2d_eval_deriv_x (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc)
Function: int gsl_interp2d_eval_deriv_x_e (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc, double * d)

  These functions return the interpolated value d = \partial z / \partial x for a given point (x,y), using the interpolation object interp, data arrays xa, ya, and za and the accelerators xacc and yacc. When x is outside the range of xa or y is outside the range of ya, the error code `GSL_EDOM` is returned.

Function: double gsl_interp2d_eval_deriv_y (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc)
Function: int gsl_interp2d_eval_deriv_y_e (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc, double * d)

  These functions return the interpolated value d = \partial z / \partial y for a given point (x,y), using the interpolation object interp, data arrays xa, ya, and za and the accelerators xacc and yacc. When x is outside the range of xa or y is outside the range of ya, the error code `GSL_EDOM` is returned.

Function: double gsl_interp2d_eval_deriv_xx (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc)
Function: int gsl_interp2d_eval_deriv_xx_e (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc, double * d)

  These functions return the interpolated value d = \partial^2 z / \partial x^2 for a given point (x,y), using the interpolation object interp, data arrays xa, ya, and za and the accelerators xacc and yacc. When x is outside the range of xa or y is outside the range of ya, the error code `GSL_EDOM` is returned.

Function: double gsl_interp2d_eval_deriv_yy (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc)
Function: int gsl_interp2d_eval_deriv_yy_e (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc, double * d)

  These functions return the interpolated value d = \partial^2 z / \partial y^2 for a given point (x,y), using the interpolation object interp, data arrays xa, ya, and za and the accelerators xacc and yacc. When x is outside the range of xa or y is outside the range of ya, the error code `GSL_EDOM` is returned.

Function: double gsl_interp2d_eval_deriv_xy (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc)
Function: int gsl_interp2d_eval_deriv_xy_e (const gsl_interp2d * interp, const double xa[], const double ya[], const double za[], const double x, const double y, gsl_interp_accel * xacc, gsl_interp_accel * yacc, double * d)

  These functions return the interpolated value d = \partial^2 z / \partial x \partial y for a given point (x,y), using the interpolation object interp, data arrays xa, ya, and za and the accelerators xacc and yacc. When x is outside the range of xa or y is outside the range of ya, the error code `GSL_EDOM` is returned.