Main Content

compare

Class: FunctionApproximation.LUTSolution
Package: FunctionApproximation

Compare numerical results of FunctionApproximation.LUTSolution to original function or lookup table

Syntax

data = compare(solution)

Description

data = compare(solution) plots the difference between the data contained in the FunctionApproximation.LUTSolution object, solution, and the original lookup table, function, or Math Function block.

Input Arguments

expand all

The solution to compare original behavior against, specified as a FunctionApproximation.LUTSolution object.

Output Arguments

expand all

Struct containing data comparing the original function or lookup table and the approximation contained in the solution.

Examples

expand all

Create a FunctionApproximation.Problem object defining the function you want to approximate.

problem = FunctionApproximation.Problem('tanh')
problem = 
  1x1 FunctionApproximation.Problem with properties:

    FunctionToApproximate: @(x)tanh(x)
           NumberOfInputs: 1
               InputTypes: "numerictype(1,16,12)"
         InputLowerBounds: -8
         InputUpperBounds: 8
               OutputType: "numerictype(1,16,15)"
                  Options: [1x1 FunctionApproximation.Options]

Use default values for all other options. Approximate the tanh function using the solve method.

solution = solve(problem)
|  ID |  Memory (bits) | Feasible | Table Size | Breakpoints WLs | TableData WL | BreakpointSpecification |             Error(Max,Current) | 
|   0 |             64 |        0 |          2 |              16 |           16 |             EvenSpacing |     7.812500e-03, 9.999998e-01 |
|   1 |           1248 |        1 |         76 |              16 |           16 |             EvenSpacing |     7.812500e-03, 4.368265e-03 |
|   2 |           1232 |        1 |         75 |              16 |           16 |             EvenSpacing |     7.812500e-03, 4.439035e-03 |
|   3 |            944 |        1 |         57 |              16 |           16 |             EvenSpacing |     7.812500e-03, 7.780470e-03 |
|   4 |            928 |        1 |         56 |              16 |           16 |             EvenSpacing |     7.812500e-03, 6.110240e-03 |
|   5 |            656 |        0 |         39 |              16 |           16 |             EvenSpacing |     7.812500e-03, 1.678519e-02 |
|   6 |            640 |        0 |         38 |              16 |           16 |             EvenSpacing |     7.812500e-03, 1.660649e-02 |
|   7 |            784 |        1 |         47 |              16 |           16 |             EvenSpacing |     7.812500e-03, 7.743777e-03 |
|   8 |            704 |        1 |         42 |              16 |           16 |             EvenSpacing |     7.812500e-03, 7.805676e-03 |
|   9 |            672 |        1 |         40 |              16 |           16 |             EvenSpacing |     7.812500e-03, 7.809550e-03 |
|  10 |            368 |        0 |         21 |              16 |           16 |             EvenSpacing |     7.812500e-03, 4.855583e-02 |
|  11 |            512 |        0 |         30 |              16 |           16 |             EvenSpacing |     7.812500e-03, 2.773526e-02 |
|  12 |            592 |        0 |         35 |              16 |           16 |             EvenSpacing |     7.812500e-03, 2.088471e-02 |
|  13 |            624 |        0 |         37 |              16 |           16 |             EvenSpacing |     7.812500e-03, 1.870074e-02 |
|  14 |            384 |        1 |         12 |              16 |           16 |          ExplicitValues |     7.812500e-03, 7.812317e-03 |
|  15 |            384 |        0 |         12 |              16 |           16 |          ExplicitValues |     7.812500e-03, 1.196141e-02 |
|  16 |            384 |        1 |         12 |              16 |           16 |          ExplicitValues |     7.812500e-03, 7.812317e-03 |

Best Solution
|  ID |  Memory (bits) | Feasible | Table Size | Breakpoints WLs | TableData WL | BreakpointSpecification |             Error(Max,Current) |
|  14 |            384 |        1 |         12 |              16 |           16 |          ExplicitValues |     7.812500e-03, 7.812317e-03 |
solution = 
  1x1 FunctionApproximation.LUTSolution with properties:

          ID: 14
    Feasible: "true"

Compare the original function and the function approximation.

data = compare(solution)

Figure contains 2 axes. Axes 1 with title Comparison of Original Function and Approximation contains 2 objects of type line. These objects represent Original, Approximation. Axes 2 with title Feasibility of Solution: Feasible AbsTol = 0.0078125 RelTol = 0.0078125 contains 3 objects of type area, line. These objects represent Feasible Region : Absolute Error <= Max Error Allowed, Max Error Allowed : max(abs(Original) * RelTol, AbsTol), Absolute Error : abs(Original - Approximation).

data = struct with fields:
    Breakpoints: [65536x1 double]
       Original: [65536x1 double]
    Approximate: [65536x1 double]

Introduced in R2018a