
classq.f(3) LAPACK classq.f(3)
NAME
classq.f 
SYNOPSIS
Functions/Subroutines
subroutine classq (N, X, INCX, SCALE, SUMSQ)
CLASSQ updates a sum of squares represented in scaled form.
Function/Subroutine Documentation
subroutine classq (integerN, complex, dimension( * )X, integerINCX, realSCALE, realSUMSQ)
CLASSQ updates a sum of squares represented in scaled form.
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 nonnegative 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.
Parameters:
N
N is INTEGER
The number of elements to be used from the vector X.
X
X is COMPLEX array, dimension (N)
The vector x as described above.
x( i ) = X( 1 + ( i  1 )*INCX ), 1 <= i <= n.
INCX
INCX is INTEGER
The increment between successive values of the vector X.
INCX > 0.
SCALE
SCALE is REAL
On entry, the value scale in the equation above.
On exit, SCALE is overwritten with the value scl .
SUMSQ
SUMSQ is REAL
On entry, the value sumsq in the equation above.
On exit, SUMSQ is overwritten with the value ssq .
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 107 of file classq.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 classq.f(3) 
