sscal1d,dscal1d(3F)					   sscal1d,dscal1d(3F)

NAME    [Toc]    [Back]

     sscal1d, dscal1d -	scales a 1D real sequence.

SYNOPSYS    [Toc]    [Back]

     Fortran :
     subroutine	sscal1d( n, alpha, array, inc)
	  integer	     n,	inc
	  real		     alpha, array(0:(n-1)*inc)
     subroutine	dscal1d( sign, n, p, array, inc, lda)
	  integer	     n,	inc
	  real*8	     alpha, array(0:(n-1)*inc)

     C :
     #include <fft.h>
     int sscal1d ( int n, float	alpha, float *array, int inc);
     int dscal1d ( int n, double alpha,	double *array, int inc);

DESCRIPTION    [Toc]    [Back]

     sscal1d and dscal1d scale a 1D real sequence of N samples.
     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.  sscal1d or	dscal1d	may be 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
     place).

     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
     Given a 1024 real values sequence.	 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.
     Fortran
	  real array(0:1024-1),	coeff(1024+15)



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sscal1d,dscal1d(3F)					   sscal1d,dscal1d(3F)



	 call scfft1dui( 1024, coeff)
	  call scfft1du( -1, 1024, array, 1, coeff)
	  call scfft1du(  1, 1024, array, 1, coeff)
	  call sscal1d(	1024, (1./real(1024)), array,1)

     C
	  #include <fft.h>
	  float	array[1024], *coeff;
	  coeff	= scfft1dui( 1024, NULL);
	  scfft1du( -1,	1024, array, 1,	coeff);
	  csfft1du(  1,	1024, array, 1,	coeff);
	  sscal1d( 1024, 1./(float)1024, array,	1);

     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, scfft1dui, dzfft1dui,	scfft1du, dzfft1du, csfft1du, zdfft1du,
     sprod1du, dprod1du


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