How to do Fourier Integrals on the HP Prime?

[medwatt]

(12-09-2019 12:23 PM)Stevetuc Wrote:  https://www.hpcalc.org/details/9041

Quote:Performs symbolic time to frequency and frequency to time calculations: calculates for a given symbolic f(t) Fourier, Laplace and Z-transformation in symbolic form, draws the complex Laplace function together with the Fourier transformation slice as a 3D plot, and calculates for a given frequency transfer function the unity pulse, dirac pulse response and bode magnitude and phase in symbolic form. Includes PDF documentation.

It uses the following to calculate the Fourier transform

Code:


//   // Function.F2 Fourier( f(t) ) = ABS( laplace( f(t) ) with (i*X) as independant )
//   ABS(simplify(laplace(F1(x),x)))
//   subst('  ',('x') = ('i*X'))
//

This is just evaluating the Laplace Transform at s=jw. The Laplace Transform used on the Prime is the single-sided LT, meaning it evaluates the integral from 0 to inf. You can use this LT to get the FT if you have a function that is right-sided. What happens if you want the FT of functions such as sin(wt), a dc signal, that span the the entire time domain ? Well, it's not possible.