The interpolation type indicates the type of curve that the data in the release function table describes. It also specifies the interpolation method to be used when performing a lookup from the release function table. The three Interp options are:
Linear—this option will cause ResSim to interpret the data in the table as a linear curve — where each pair of points (2 consecutive rows in the table) are connected by a straight line. And, linear interpolation is used when performing a lookup on the table to obtain a release. "Figure: Example Release Function Rule using Linear Interpolation" shows an example of a release function with the interpolation type set to Linear. The thumbnail plot shows how ResSim interprets the data as a linear curve (a series of straight line segments).
Figure: Example Release Function Rule using Linear Interpolation
Step — this option will cause ResSim to interpret the data in the release function table as a step function — where the release value in each row is held constant (drawn horizontal) until changed by the next row. Step interpolation is used to determine a release value when performing a lookup on the table—if the independent value falls between rows in the table, the value of the release (the dependent variable) is the release value in the row above. "Figure: Step Interpolation" shows the thumbnail plot for the same function shown in "Figure: Example Release Function Rule using Linear Interpolation" but with the interpolation type set to Step.
Figure: Step Interpolation
Cubic — this option will cause ResSim to interpret the data in the release function table as a 3-point Cubic Spline curve. When a value for the independent variable is used to perform a lookup on the table to obtain an associated release (the dependent variable), the release is determined by the cubic spline function defined with each three consecutive rows in the table. "Figure: Cubic Interpolation" shows the thumbnail plot for the same function shown in "Figure: Example Release Function Rule using Linear Interpolation but with the interpolation type set to Cubic.
