CRFFT2(3F)							    CRFFT2(3F)

NAME    [Toc]    [Back]

     CRFFT2 - Calculate	a complex-to-real Fourier synthesis/analysis.

DESCRIPTION    [Toc]    [Back]

     A subroutine that calculates a Fourier synthesis if the sign of IX	is
     negative and a Fourier analysis if	the sign of IX is positive.

      Call from	FORTRAN:

	    CALL CRFFT2(init,ix,n,x,work,y)

	  init	<>0  Generates sine and	cosine tables in WORK
		= 0  Calculates	Fourier	transforms using sine and
		   cosine tables of previous call.
	  ix	> 0  Calculates	Fourier	analysis
		<=0  Calculates	Fourier	synthesis.
	  n	Size of	Fourier	transform; 2**m	where 2<=m.
	  x	Input vector.  Vector of (n/2)+1 complex values.
	  work	Working	storage.  Vector of (3/2)n+2 complex values.
	  y	Result vector.	Vector of n complex values.

     For equations and other additional	information, see the CRAY-1 Computer
     Systems - Library Reference Manual, SR-0014, page 4-53.


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