2.11.1.3 ifft1

1 Menu Information
2 Brief Information
3 Command Line Usage
4 X-Function Execution Options
5 Variables
6 Examples
7 More Information
8 Related X-Functions

Menu Information

Analysis: Signal Processing: FFT: IFFT

Brief Information

Compute inverse fourier transform

Command Line Usage

1. ifft1 ix:=Col(2);

2. ifft1 ix:=(Col(2),Col(3));

3. ifft1 ix:=Col(2) win:=hanning correct:=power;

4. ifft1 ix:=Col(2) unwrap:=1;

5. ifft1 ix:=Col(2) plot:=amp;

X-Function Execution Options

Please refer to the page for additional option switches when accessing the x-function from script

Variables

Display Name	Variable Name	I/O and Type	Default Value	Description
Input	ix	Input vector<complex>	<active>	Specifies the input signal, which could be complex. The real and imaginary parts of the signal can be saved in two different columns or in a single column. The default is <Active>, which corresponds to the active dataset.
Sampling Interval	interval	Input double	1	Specifies the sampling interval. The default is <Auto>, which corresponds to automatically-computed interval. Please see the Algorithm section for more details.
Plot	plot	Input int	ap	Specifies what will be plotted in the preview window and outputted to the result graph sheet. Option list 0=none:None None 1=ap:Amplitude /Phase The amplitude and phase of the result 2=real:Real The real parts of the result data points 3=img:Imaginary The imaginary parts of the result data points 4=amp:Amplitude The amplitudes of the result 5=phase:Phase The phase of the result
Undo Shift Input Data	shift	Input int	1	Specifies whether the input is generated by a FFT with the results shifted. If this option is checked, the input data points will first be swapped in order to undo the effect of shifting.
Window	win	Input int	Hamming	Specifies the window function used to suppress the leakage. Please see the algorithm section for further details of these window types. Option list 0=rect:Rectangle Rectangular window 1=welch:Welch Welch window 2=tri:Triangular Triangular window 3=bartlett:Bartlett Bartlett window 4=hanning:Hanning Hanning window 5=hamming:Hamming Hamming window 6=blackman:Blackman Blackman window 7=gauss:Gaussian Gaussian window 8=kaiser:Kaiser Kaiser window
Alpha	alpha	Input double	0	This variable is only available when window type is Gaussian. It specifies the Alpha parameter (the reciprocal of the standard deviation) for Gaussian window.
Beta	beta	Input double	0	This variable is only available when window type is Kaiser. It specifies the Beta parameter for Kaiser window.
Window Correction	correct	Input int	amplitude	Specifies the Window Correction Factor used to correct the alteration made by applying a window to the input data. Option list none:None No correction is applied. amp:Amplitude Amplitude Correction is applied. power:Power Energy Correction is applied.
Factor	factor	Input int	ee	Specifies whether the Electrical Engineering or Science convention is used to set the sign of the exponential phase factor. Option list ee :-1 (Electrical Engineering) The phase factor sign will be the opposite of the Science option. science:+1 (Science) The phase factor will be set according to the formulae listed in page 503 of Numerical Recipes in C, 2nd edition
Unwrap Phase	unwrap	Input int	1	Specifies whether the phase should be unwrapped. If wrapped, phase data will be defined in the range of -180° to +180°
Result Data Sheet	rd	Output ReportData	[<input>]<new>	Specifies the output data sheet.
Result Graph Sheet	rt	Output ReportTree	[<input>]<new template:=graph>	Specifies the output graph sheet.

Examples

1. To perform an inverse Fourier transform using default settings on complex data whose real parts and imaginary parts are in columns 2 and 3 respectively, use the script command:

ifft1 ix:=(Col(2), Col(3))

2. To perform an inverse Fourier transform on data using a pre-saved smoothing theme file, save your preferences in the advanced options in the ifft1 dialog. Execute it by typing the following script command, using your own saved-theme title:

ifft1 -t "my ifft1 theme.oth"