Help for SWAP

PURPOSE

Switches the locations of the quadrants of an image or a complex fft.
Upper left goes to lower right.
Lower right goes to upper left.
Upper right goes to lower left.
Lower left goes to upper right.

The main purpose of SWAP is to move the origin or DC term of the fft located
at (1,1) to the center of the image at (nl/2,ns/2).

EXECUTION

fft22 a b
swap b c 

RESTRICTIONS

Image must have an even number of lines and samples.

Cognizant Programmer:  JJ Lorre   July 1998

PARAMETERS: