redhat man page for classq

CLASSQ(l)								 )								 CLASSQ(l)

NAME
       CLASSQ - return the values scl and ssq such that  ( scl**2 )*ssq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq,

SYNOPSIS
       SUBROUTINE CLASSQ( N, X, INCX, SCALE, SUMSQ )

	   INTEGER	  INCX, N

	   REAL 	  SCALE, SUMSQ

	   COMPLEX	  X( * )

PURPOSE
       CLASSQ returns the values scl and ssq such that ( scl**2 )*ssq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq, where x( i ) = abs( X( 1 +
       ( i - 1 )*INCX ) ). The value of sumsq is assumed to be at least unity and the value of ssq will then satisfy

	  1.0 .le. ssq .le. ( sumsq + 2*n ).

       scale is assumed to be non-negative and scl returns the value

	  scl = max( scale, abs( real( x( i ) ) ), abs( aimag( x( i ) ) ) ),
		 i

       scale and sumsq must be supplied in SCALE and SUMSQ respectively.  SCALE and SUMSQ are overwritten by scl and ssq respectively.

       The routine makes only one pass through the vector X.

ARGUMENTS
       N       (input) INTEGER
	       The number of elements to be used from the vector X.

       X       (input) COMPLEX array, dimension (N)
	       The vector x as described above.  x( i )  = X( 1 + ( i - 1 )*INCX ), 1 <= i <= n.

       INCX    (input) INTEGER
	       The increment between successive values of the vector X.  INCX > 0.

       SCALE   (input/output) REAL
	       On entry, the value  scale  in the equation above.  On exit, SCALE is overwritten with the value  scl .

       SUMSQ   (input/output) REAL
	       On entry, the value  sumsq  in the equation above.  On exit, SUMSQ is overwritten with the value  ssq .

LAPACK version 3.0						   15 June 2000 							 CLASSQ(l)