slassq.f - Man Page
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 (integer N, real, dimension( * ) X, integer INCX, real SCALE, real SUMSQ)
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:
December 2016
Definition at line 105 of file slassq.f.
Author
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Referenced By
The man page slassq(3) is an alias of slassq.f(3).
Tue Nov 14 2017 Version 3.8.0 LAPACK