classq(3)

NAME

SUBROUTINE CLASSQ( N, X, INCX, SCALE, SUMSQ )
    INTEGER        INCX, N
    REAL           SCALE, SUMSQ
    COMPLEX        X( * )

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 as
sumed 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 re
spectively. SCALE and SUMSQ are overwritten by scl and ssq re
spectively.
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 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) REAL: On entry, the value scale in the equation above.; On exit, SCALE is overwritten with the value scl .
SUMSQ (input/output) REAL: On entry, the value sumsq in the equation above.; On exit, SUMSQ is overwritten with the value ssq .
LAPACK version 3.0 15 June 2000