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+--- Thread: Chebyshev Approximations of an Analytic Function (/thread-18797.html)
Chebyshev Approximations of an Analytic Function - cdeaglejr - 09-12-2022 09:39 AM
// program demo_chebyshev HP Prime
// September 12, 2022
// This program demonstrates the procedures for calling
// several Chebyshev subroutines. These subroutines can be
// used to approximate the integral, derivative, and
// function value of a user-defined analytic function.
// This program demonstrates the use of the Chebyshev
// subroutines for evaluating information about
// f(x) = x^2 * (x^2 - 2.0) * sin(x)
// NOTE: current array allocations require maximum degree <= 20
The software allows the user to define a problem using the following inputs coded at the beginning of the main program.
// maximum degree of the chebyshev approximation
ndeg := 15;
// lower limit of the evaluation interval
xlower := 1.0;
// upper limit of the evaluation interval
xupper := 2.0;
// number of terms in the chebyshev approximation
nterms := 10;
// x argument for evaluation
x := 1.5;
The following is the source code for the user-defined function for this example. This is where the user should define his or her function of interest.
user_func(x)
// user-defined function subroutine
///////////////////////////////////
BEGIN
LOCAL fx;
fx := (x * x) * (x * x - 2.0) * sin(x);
return fx;
END;