Provided by: liblapack-doc_3.3.1-1_all
LAPACK-3 - returns the values scl and ssq such that ( scl**2 )*ssq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq,
SUBROUTINE ZLASSQ( N, X, INCX, SCALE, SUMSQ ) INTEGER INCX, N DOUBLE PRECISION SCALE, SUMSQ COMPLEX*16 X( * )
ZLASSQ returns the values scl and ssq such that 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.
N (input) INTEGER The number of elements to be used from the vector X. X (input) COMPLEX*16 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) DOUBLE PRECISION On entry, the value scale in the equation above. On exit, SCALE is overwritten with the value scl . SUMSQ (input/output) DOUBLE PRECISION On entry, the value sumsq in the equation above. On exit, SUMSQ is overwritten with the value ssq . LAPACK auxiliary routine (version 3.2) April 2011 ZLASSQ(3lapack)