Frequency to Time FFT

A Frequency to Time FFT study step, which you can add to a time-dependent study, performs an inverse FFT (or, alternatively, the nonuniform Fourier transform) from the frequency domain (input) to the time domain (output). As the default solver it adds an FFT solver.

Syntax

model.study(stdname).create(fname, "FreqToTimeFFT");

model.study(stdname).feature(fname).set(pname,value);

Description

Study step.

The following properties are available.

Table 6-128: Properties for Study Settings
Property	Value	Default	Description
addstatsol	on \| off	off	Add stationary solution.
fftoutrange	Numeric vector		Output times.
fftscaling	cont \| discrete	cont	Use a discrete or continuous scaling for the Fourier transform.
fftwinalpha	Real scalar	0.5	Window parameter for a Tukey window.
fftwincenterinv	Real scalar	50	Window center for a Gaussian window function.
fftwincutoff	Real scalar	1	Cutoff fraction for window function in [0, 1].
fftwindev	Real scalar	1	Standard deviation for a Gaussian window function.
fftwindowinv	on \| off	off	Use window function.
fftwinexpr	String	1	Expression for window function (when set to fromexpr). Can be expressed in terms of t, freq, niterFFTin, and niterFFTout (if applicable).
fftwinmaxinv	Real scalar	100	Maximum (end) value for window.
fftwinmininv	Real scalar	0	Minimum (start) value for window.
fftwintypeinv	fromexpr \| cutoff \| rectangle \| gauss \| hamming \| hanning \| blackman \| tukey	fromexpr	Method for window function.
linpmethod	sol \| init	sol	Prescribe the input values using a solution or an initial expression.
linpsol	String		Solution that defines input values for the FFT study step.
linpsoluse	String		Subsolution that defines the input values for the FFT study step/FFT solver.
linpstudy	String		Study that defines input values for the FFT study step.
statmanualsolnum	Integer	1	Index to stationary solution to add.
statmethod	sol \| init	sol	For an added stationary solution, use a solution or initial expression.
statsolnum	auto \| first \| last \| interp \| manual \| positive integer	auto	Selection method for stationary solution to add.
statstudy	String	zero	Study from which the added stationary solution is chosen.
statt	String		Specify time for interpolated solution to add.
tunit	String	s	Time unit.
winpunit	String	Hz	Frequency unit for window.

Table 6-129: Properties for Physics and Variables Selection
Property	Value	Default	Description
activate	String Map		See Physics and Variables Selection
activateCoupling	String Map		See Physics and Variables Selection
activaterom	String Map		See Physics and Variables Selection
disabledcommon	Reference Array		See Physics and Variables Selection
disabledcoordinatesystems	Reference Array		See Physics and Variables Selection
disabledcoupling	Reference Array		See Physics and Variables Selection
disabledpair	Reference Array		See Physics and Variables Selection
disabledphysics	Reference Array		See Physics and Variables Selection
disabledreduced	Reference Array		See Physics and Variables Selection
disabledvariables	Reference Array		See Physics and Variables Selection
disableFrameControl	Reference Array		See Physics and Variables Selection
discretization	String Map		See Physics and Variables Selection
equationform	String Map		See Physics and Variables Selection
equationform_freq	String Map		See Physics and Variables Selection
equationform_freq_src	String Map		See Physics and Variables Selection
reconstructors	String Map		See Physics and Variables Selection
useadvanceddisable	on \| off	off	See Physics and Variables Selection.

Table 6-130: Properties for Values of Dependent Variables
Property	Value	Default	Description
notlistsolnum	Vector of integers	[1]	Indices to selected solutions for values for variables not solved for.
notmanualsolnum	Vector of integers	[1]	Indices to solutions for values for variables not solved for.
notsolmethod	init \| sol	init	Method for values for variables not solved for.
notsolnum	auto \| all \| first \| last \| from_list \| interp \| manual \| positive integer	auto	Solution selection for values for variables not solved for.
notstudy	String		Reference to study or "zero" for zero solution.
nott	String		Specify time for interpolated solution of values for variables not solved for.
storesel	Vector of strings		Selections defining which field data to store.
usestoresel	all \| selection	all	Store fields in output.

Table 6-131: Property for Mesh selection
Property	Value	Default	Description
mesh	Vector of strings		Select meshes for geometries. The length of the vector is two times the number of geometries. Example value when two geometries geom1 and geom2 are available is: new String[]{"geom1","mesh1","geom2", "mesh2"}.