Process data with PROC G3GRID. The PARTIAL option specifies that a spline be used to estimate the derivatives for the biquintic polynomial interpolation. The NEAR= option specifies the number of nearest neighbors to be used for computing the estimates of the first, and the second derivatives.

proc g3grid data=nums out=partial; grid y*x=z / partial near=8 axis1=-5 to 5 by .5 axis2=-5 to 5 by .5; run;