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## Fourier Transforms

CUPLOT has a set of Fourier Transform commands. The transform is stored in temporary arrays. You can store the inverse transform into a frame/curve slot, after applying optional notch or band pass filters. You can also store the phase and/or amplitude into a slot. Only the data with the x window is transformed.

FF
takes the fourier transform of the data. The result is stored in a temporary array and can only be viewed using the FP command.

FP
plots the frequency and magnitude.

```
Command[ ]? SH 45436

Command[ ]? DE DYF-6810-1 ;

Command[ ]? R			!read the data

Command[ ]? FF			!transform the data

Frame[F1C1]? F1

Command[ ]? FP			!plot the transform

```

FR
windows the transform plot on the frequency range.

FY
windows the transform plot on the amplitude range.

FN
notches a frequency range of the transform.

FB
sets a frequency range bandpass.

FU
stores the inverse transform back as a data element. This clears the transform array.

```
Command[ ]? FF F1			!transform F1

Command[ ]? FN 395 405			!notch out freq 395 to 405

Command[ ]? FU

Frame to store inverse transform[F1C1]? F2

```

FO
sets or clears the flag to remove the linear (DC) offset when storing the inverse with the FC command.

FS
stores the phase or amplitude as a data element.

```
Command[ ]? FF F1			!transform F1

Command[ ]? FS

Store Phase or Amplitude[A]? A

Frame/curve[F1C1]? F2

```

FC
correlates two frames, f * g.

FV
convolves for response function, f / g.

F2
plots the amplitute and phase of g.

FH
gives a list of the Fourier transform commands.

Marilee Thompson
Fri Jul 11 12:49:48 EDT 1997