Overview
A function lookup table is a method by which you can approximate
a function by a table with a finite number of points (X,Y). Function
lookup tables are essential to many fixed-point applications. The
function you want to approximate is called the ideal function.
The X values of the lookup table are called the breakpoints.
You approximate the value of the ideal function at a point by linearly
interpolating between the two breakpoints closest to the point.
In creating the points for a function lookup table, you generally
want to achieve one or both of the following goals:
This tutorial shows you how to create function lookup tables
using the function fixpt_look1_func_approx.
You can optimize the lookup table to minimize the number of data points,
the error, or both. You can also restrict the spacing of the breakpoints
to be even or even powers of two to speed up computations using the
table.
This tutorial also explains how to use the function fixpt_look1_func_plot to find the worst-case
error of a lookup table and plot the errors at all points.
 | Tutorial: Producing Lookup Table Data | | Worst-Case Error for a Lookup Table |  |
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