The SFIT function determines a polynomial fit to a surface and returns a fitted array. The function fitted is:

This routine is written in the IDL language. Its source code can be found in the file ```
sfit.pro
```

in the ```
lib
```

subdirectory of the IDL distribution.

Create a grid from zero to six radians in the X and Y directions:

X = (FINDGEN(61)/10) # REPLICATE(1,61)

Evaluate a function at each point:

Compute a sixth-degree polynomial fit to the function data:

Display the original function on the left and the fitted function on the right, using

WINDOW, XSIZE = 800, YSIZE = 400

!P.MULTI = [0, 2, 1] *;
Set up side-by-side plots.*

!P.BACKGROUND = 255 *;
Set background color to white.*

!P.COLOR = 0 *;
Set plot color to black.*