DLASSQ(3)      LAPACK routine of NEC Numeric Library Collection      DLASSQ(3)



NAME
       DLASSQ

SYNOPSIS
       SUBROUTINE DLASSQ (N, X, INCX, SCALE, SUMSQ)



PURPOSE
            DLASSQ  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.




ARGUMENTS
           N         (input)
                     N is INTEGER
                     The number of elements to be used from the vector X.

           X         (input)
                     X is DOUBLE PRECISION 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)
                     INCX is INTEGER
                     The increment between successive values of the vector X.
                     INCX > 0.

           SCALE     (input/output)
                     SCALE is DOUBLE PRECISION
                     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)
                     SUMSQ is DOUBLE PRECISION
                     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 routine                  31 October 2017                      DLASSQ(3)