sscalm1d,dscalm1d(3F)					 sscalm1d,dscalm1d(3F)

NAME    [Toc]    [Back]

     sscalm1d, dscalm1d	- scales Multiple 1D real sequences.

SYNOPSYS    [Toc]    [Back]

     Fortran :
     subroutine	sscalm1d( n, p,	alpha, array, inc, lda)
	  integer	     n,	p, inc,	lda
	  real		     alpha, array(lda,p)
     subroutine	dscalm1d( n, p,	alpha, array, inc, lda)
	  integer	     n,	p, inc,	lda
	  real*8	     alpha, array(lda,p)

     C :
     #include <fft.h>
     int sscalm1d ( int	n, int p, float	alpha, float *array,
	       int inc,	int lda);
     int dscalm1d ( int	n, int p, double alpha,	double *array,
	       int inc,	int lda);

DESCRIPTION    [Toc]    [Back]

     sscalm1d and dscalm1d scale the P real sequences of N samples each.
     The Fourier Transforms are	not normalized so the succession DirectInverse
 transform scales the input	data by	a factor equal to the size of
     the transform.  Often sscalm1d or dscalm1d	are used to scale back the
     result.

PARAMETERS    [Toc]    [Back]

     N Integer,	the number of samples in each sequence.	 Unchanged on exit.

     P Integer,	the number of sequences.  Unchanged on exit.

     Alpha scaling floating point value.

     ARRAY Array containing the	samples	of the sequence	to be scaled (in
     place0.

     INC Integer, increment between two	consecutive elements of	a sequence.
     Unchanged on exit.

     LDA Integer, leading dimension: increment between the first samples of
     two consecutive sequences.	 Unchanged on exit.


Example	of Calling Sequence
     Working on	64 sequences of	1024 real values each.	We successively	apply
     a Direct Fourier Transform, an Inverse Fourier Trasnform and finally
     scale back	the result by a	factor 1/N (1/1024.)-
     This sequence DirectFFT-InverseFFT-Scaling	is equivalent to the identity
     operator and the final sequence should be equal (with round-off
     precision)	to the initial sequence.
     Elements of each sequence are stored with increment (stride) 1, and the



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sscalm1d,dscalm1d(3F)					 sscalm1d,dscalm1d(3F)



     offset between the	first element of two succesive sequence	(leading
     dimension)	is 1026	(1026 >= 1024+2).
     Fortran
	  real array(0:1026-1,0:64-1), coeff(1024+15)
	  call scfftm1dui( 1024, coeff)
	  call scfftm1du( -1, 1024, 64,	array, 1, 1026,	coeff)
	  call csfftm1du(  1, 1024, 64,	array, 1, 1026,	coeff)
	  call sscalm1d(1024,64,(1./real(1024)),array,1,1026)

     C
	  #include <fft.h>
	  float	array[64*1026],	*coeff;
	  coeff	= scfftm1dui( 1024, NULL);
	  scfftm1du( -1, 1024, 64, array, 1, 1026, coeff);
	  csfftm1du(  1, 1024, 64, array, 1, 1026, coeff);
	  sscalm1d( 1024, 64, 1./(float)1024, array, 1,	1026);

     NOTE_1 : The Direct and Inverse transforms	should use opposite signs -
     Which one is used (+1 or -1) for Direct transform is just a matter	of
     convention
     NOTE_2 : The Fourier Transforms are not normalized	so the succession
     Direct-Inverse transform scales the input data by a factor	equal to the
     size of the transform.

SEE ALSO    [Toc]    [Back]

     fft, scfftm1dui, dzfftm1dui, scfftm1du, dzfftm1du,	csfftm1du, zdfftm1du,
     sprodm1du,	dprodm1du


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