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Figure 11: Scattered surface plot

Figure 12: Smoothed surface plot

SURFACE lets you plot data as a function of two variables. You can get an isometric graph of raw data or of smoothed data. After you select SURFACE from the main menu, you will be prompted for the axis variables. You can set constraints and the axis ranges. If you select the scatter plot which is the default, you will get a symbol plotted on an isometric graph for each point that satisfies the constraints. See Figure 11. If you select to interpolate, you can choose to use the x and y values of your database for the grid. An interpolation of z is done at these coordinates as shown in Figure 12. Alternatively, you can specify an evenly spaced grid for either x or y and z will be interpolated on that grid. The interpolation is done by the IMSL routine SURF . SURF ``computes a smooth bivariate interpolant to scattered data which is locally a quintic polynomial in two variables.''[7] To produce a graph with SURFACE:

<2;> X, Y, Z? < >:  radius time ne

<5=S;> Set X, Y, Z, XA, YA, ZA, C, T, Sc, In? <C>:
\* Options are:
 1) X           <RADIUS>
 2) Y           <TIME>
 3) Z           <NE>
 4) XAxis range <  0.000E+00, 0.000E+00, LIN >
 5) YAxis range <  0.000E+00, 0.000E+00, LIN >
 6) ZAxis range <  0.000E+00, 0.000E+00, LIN >
 7) Constraints  < >
 8) Title        <>
 9) Scatter plot of raw data                  <ON>  or
10) Interpolate the data onto a regular grid  <OFF>

<5=S;> Set X, Y, Z, XA, YA, ZA, C, T, Sc, In? <C>:  ;

Marilee Thompson
Fri Jul 11 17:05:56 EDT 1997