Provided by: liblapack-doc_3.3.1-1_all
LAPACK-3 - returns the values scl and smsq such that ( scl**2 )*smsq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq,
SUBROUTINE SLASSQ( N, X, INCX, SCALE, SUMSQ ) INTEGER INCX, N REAL SCALE, SUMSQ REAL X( * )
SLASSQ returns the values scl and smsq such that 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.
N (input) INTEGER The number of elements to be used from the vector X. X (input) 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 (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 scl , the scaling factor for the sum of squares. SUMSQ (input/output) 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. LAPACK auxiliary routine (version 3.2) April 2011 SLASSQ(3lapack)