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


 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

          N is INTEGER


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

X

          X is COMPLEX array, dimension (N)


          The vector x as described above.


             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 REAL


          On entry, the value  scale  in the equation above.


          On exit, SCALE is overwritten with the value  scl .

SUMSQ

          SUMSQ is REAL


          On entry, the value  sumsq  in the equation above.


          On exit, SUMSQ is overwritten with the value  ssq .

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NAG Ltd.

September 2012