AC - Auto Correlation ||

(02/25/00)

PURPOSE

Computes the auto-correlation function of a imag/volume by using the Fourier transform relationship.   Example.

SEE ALSO

AC N [Auto Correlation - Normalized ||]
AC MS [Auto Correlation - Masked and normalized ||]
CC [Cross Correlation ||]
CC N [Cross Correlation - Normalized ||]
CN [Convolution ||]
CN N [Convolution - Normalized ||]
FT [Fourier Transform ||]

USAGE

.OPERATION: AC

.INPUT FILE: PIC001
[Enter the name of the picture to be auto-correlated.]

.OUTPUT FILE: ACF001
[Enter name of the file which will contain the auto-correlation coefficients.]

NOTES

  1. On completion of this operation, the output file will contain the auto-correlation function. The origin is at (NX/2 + 1, NY/2 + 1, NZ/2 + 1) The ACF is not normalized.

  2. The type of input data can be either real or Fourier.

  3. If the data cannot fit into the memory, use the 'FT' and 'SQ' commands to calculate the ACF:
       FT
       INPUT
       FOUR

       SQ
       FOUR
       MODFT

       FT
       MODFT
       ACF

    WARNING: The orgin of the ACF calculated in this way is in (1,1,1).

SUBROUTINES

FMRS_2, FMRS_1, FMRS_3, ACRS_2, ACRS_3

CALLER

CORR1

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