Use Lookup Table Approximation Functions

The following steps summarize how to use the lookup table approximation functions.

  1. Define:

    1. The ideal function to approximate

    2. The range, xmin to xmax, over which to find X and Y data

    3. The fixed-point implementation: data type, scaling, and rounding method

    4. The maximum acceptable error, the maximum number of points, and the spacing

  2. Run the fixpt_look1_func_approx function to generate X and Y data.

  3. Use the fixpt_look1_func_plot function to plot the function and error between the ideal and approximated functions using the selected X and Y data, and to calculate the error and the number of points used.

  4. Vary input criteria, such as errmax, nptsmax, and spacing, to produce sets of X and Y data that generate functions with varying worst-case error, number of points required, and spacing.

  5. Compare results of the number of points required and maximum absolute error from various runs to choose the best set of X and Y data.