NAME

       dlassq.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dlassq (N, X, INCX, SCALE, SUMSQ)
           DLASSQ updates a sum of squares represented in scaled form.

Function/Subroutine Documentation

   subroutine dlassq (integerN, double precision, dimension( * )X, integerINCX, double
       precisionSCALE, double precisionSUMSQ)
       DLASSQ updates a sum of squares represented in scaled form.

       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.

       Parameters:
           N

                     N is INTEGER
                     The number of elements to be used from the vector X.

           X

                     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

                     INCX is INTEGER
                     The increment between successive values of the vector X.
                     INCX > 0.

           SCALE

                     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

                     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.

       Author:
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Date:
           September 2012

       Definition at line 104 of file dlassq.f.

Author

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