MagicPlot Manual

Plotting and nonlinear fitting software

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fft

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Fast Fourier Transform (FFT)

Open table with initial data and use `Analysis → Fast Fourier Transform` menu item to perform FFT.

Formulas

Discrete Fourier Transform Formulas

MagicPlot uses 'electrical engineering' convention to set the sign of the exponential phase factor of FFT as follows from the table below. 1)

Normalize Forward
Transform
Forward Transform
(Signal→Spectrum)
Inverse Transform
(Spectrum→Signal)
Unchecked
Checked

Here are complex signal components and are complex spectrum components, .

Sampling Column Formulas

Center Zero
Frequency
Sampling Column Values
Unchecked
Checked

Here is given sampling interval of initial data.

Parameters

 Sampling Interval Sampling interval is used to compute the data in resulting sampling column. If `Get from` box is set, MagicPlot will calculate sampling interval as difference between two beginning values from given column. You can set sampling interval manually by checking `Set manually` box. Columns with real and imaginary components of data. If your data is only real, select `` imaginary item Transform direction Divide forward transform result by number of points N If selected, after forward Fourier transform the two parts of spectrum will be rearranged so that the lower frequency components are in the center; the opposite rearrangement of spectrum will be done before inverse transform if any.
1)
Most scientific applications uses the same sign conventions. But note, that the sign of exponential phase factor in Numerical Receipts in C, 2nd edition, p. 503 is the opposite