Package Modelica.​Math.​FastFourierTransform.​Internal
Internal library that should not be used directly by a user

Information

This icon shall be used for a package that contains internal classes not to be directly utilized by a user.

Extends from Modelica.​Icons.​InternalPackage (Icon for an internal package (indicating that the package should not be directly utilized by user)).

Package Contents

Function Modelica.​Math.​FastFourierTransform.​Internal.​rawRealFFT
Compute raw Fast Fourier Transform for real signal vector

Information

Syntax

(info, amplitudes, phases) = rawRealFFT(u);

Description

Raw interface to a function of the Kiss_FFT package to compute the FFT of a real, sampled signal. The input argument of this function is a Real vector u. size(u,1) must be even. An efficient computation is performed, if size(u,1) = 2^a*3^b*5^c (a,b,c Integer ≥ 0). The function computes a real FFT (Fast Fourier Transform) of u and returns the result in form of the outputs amplitudes and phases. Argument info provides additional information:

   info = 0: Successful FFT computation.
   info = 1: size(u,1) is not even.
   info = 2: size(work,1) is not correct (= a protected utility array).
   info = 3: Another error.

Note, in the original publication about the efficient computation of FFT (Cooley and Tukey, 1965), the number of sample points must be 2^a. However, all newer FFT algorithms do not have this strong restriction and especially not the open source software KissFFT from Mark Borgerding used in this function.

References

Mark Borgerding (2010):

KissFFT, version 1.3.0. http://sourceforge.net/projects/kissfft/.
 

James W. Cooley, John W. Tukey (1965):

An algorithm for the machine calculation of complex Fourier series. Math. Comput. 19: 297-301. doi:10.2307/2003354.
 

Martin R. Kuhn, Martin Otter, Tim Giese (2015):

Model Based Specifications in Aircraft Systems Design. Modelica 2015 Conference, Versailles, France, pp. 491-500, Sept.23-25, 2015. Download from: http://www.ep.liu.se/ecp/118/053/ecp15118491.pdf

Example

(info, A, phases) = realFFT({0,0.1,0.2,0.4,0.5, 0.6})

Extends from Modelica.​Icons.​Function (Icon for functions).

Inputs

Outputs

Function Modelica.​Math.​FastFourierTransform.​Internal.​prime235Factorization
Factorization of an integer in prime numbers 2,3,5

Information

Syntax

(success, e2, e3, e5) = prime235Factorization(n);

Description

Compute the factorization of input Integer n in prime numbers 2, 3, and 5. If this is possible, success = true and e2 is the number of prime numbers2, e3 the number of prime numbers 3 and e5 the number of prime numbers 5. If this is not possible, success = false, and e2, e3, e5 are dummy values.

Example

(success, e2, e3, e5) = prime235Factorization(60)   // success=true, e2=2, e3=1, e5=1 (= 2^2*3^1*5^1)
(success, e2, e3, e5) = prime235Factorization(7)    // success=false

Extends from Modelica.​Icons.​Function (Icon for functions).

Inputs

Outputs