|void surfun (zfun, ixpts, xdel, iypts, ydel)||D3PLT.C||Level 3|
|float (*zfun)(float,float)||A function that determines the height of the surface from
the x-y plane.
The arguments of zfun are float x, float y.
|int ixpts||Number of points interpolated between grid lines in the x direction.|
|float xdel||Interval between grid lines on the x axis in units of the x axis.|
|int iypts||Number of points interpolated between grid lines in the y direction.|
|float ydel||Interval between grid lines on the y axis in units of the y axis.|
|surfun() draws the surface z = zfun(x, y) as a grid of lines parallel to the x and y axes. By increasing the values of ixpts and iypts, the smoothness of the surface will be increased.|