slassq.f man page

slassq.f —

Synopsis

Functions/Subroutines

subroutine slassq (N, X, INCX, SCALE, SUMSQ)
SLASSQ updates a sum of squares represented in scaled form.

Function/Subroutine Documentation

subroutine slassq (integerN, real, dimension( * )X, integerINCX, realSCALE, realSUMSQ)

SLASSQ updates a sum of squares represented in scaled form.

Purpose:

SLASSQ  returns the values  scl  and  smsq  such that

   ( scl**2 )*smsq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq,

where  x( i ) = X( 1 + ( i - 1 )*INCX ). The value of  sumsq  is
assumed to be non-negative and  scl  returns the value

   scl = max( scale, abs( x( i ) ) ).

scale and sumsq must be supplied in SCALE and SUMSQ and
scl and smsq are overwritten on SCALE and SUMSQ 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 REAL array, dimension (N)
The vector for which a scaled sum of squares is computed.
   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  scl , the scaling factor
for the sum of squares.

SUMSQ

SUMSQ is REAL
On entry, the value  sumsq  in the equation above.
On exit, SUMSQ is overwritten with  smsq , the basic sum of
squares from which  scl  has been factored out.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 104 of file slassq.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

slassq(3) is an alias of slassq.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK