julie
be91086043
Those are just cosmetic changes to update version number and various other minor change.
103 lines
3.0 KiB
FortranFixed
103 lines
3.0 KiB
FortranFixed
SUBROUTINE CLASSQ( N, X, INCX, SCALE, SUMSQ )
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*
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* -- LAPACK auxiliary routine (version 3.2) --
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* -- LAPACK is a software package provided by Univ. of Tennessee, --
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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* November 2006
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*
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* .. Scalar Arguments ..
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INTEGER INCX, N
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REAL SCALE, SUMSQ
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* ..
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* .. Array Arguments ..
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COMPLEX X( * )
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* ..
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*
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* Purpose
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* =======
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*
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* CLASSQ returns the values scl and ssq such that
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*
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* ( scl**2 )*ssq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq,
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*
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* where x( i ) = abs( X( 1 + ( i - 1 )*INCX ) ). The value of sumsq is
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* assumed to be at least unity and the value of ssq will then satisfy
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*
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* 1.0 .le. ssq .le. ( sumsq + 2*n ).
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*
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* scale is assumed to be non-negative and scl returns the value
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*
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* scl = max( scale, abs( real( x( i ) ) ), abs( aimag( x( i ) ) ) ),
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* i
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*
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* scale and sumsq must be supplied in SCALE and SUMSQ respectively.
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* SCALE and SUMSQ are overwritten by scl and ssq respectively.
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*
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* The routine makes only one pass through the vector X.
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*
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* Arguments
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* =========
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*
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* N (input) INTEGER
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* The number of elements to be used from the vector X.
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*
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* X (input) COMPLEX array, dimension (N)
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* The vector x as described above.
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* x( i ) = X( 1 + ( i - 1 )*INCX ), 1 <= i <= n.
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*
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* INCX (input) INTEGER
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* The increment between successive values of the vector X.
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* INCX > 0.
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*
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* SCALE (input/output) REAL
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* On entry, the value scale in the equation above.
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* On exit, SCALE is overwritten with the value scl .
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*
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* SUMSQ (input/output) REAL
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* On entry, the value sumsq in the equation above.
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* On exit, SUMSQ is overwritten with the value ssq .
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*
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* =====================================================================
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*
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* .. Parameters ..
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REAL ZERO
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PARAMETER ( ZERO = 0.0E+0 )
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* ..
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* .. Local Scalars ..
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INTEGER IX
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REAL TEMP1
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC ABS, AIMAG, REAL
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* ..
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* .. Executable Statements ..
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*
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IF( N.GT.0 ) THEN
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DO 10 IX = 1, 1 + ( N-1 )*INCX, INCX
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IF( REAL( X( IX ) ).NE.ZERO ) THEN
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TEMP1 = ABS( REAL( X( IX ) ) )
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IF( SCALE.LT.TEMP1 ) THEN
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SUMSQ = 1 + SUMSQ*( SCALE / TEMP1 )**2
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SCALE = TEMP1
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ELSE
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SUMSQ = SUMSQ + ( TEMP1 / SCALE )**2
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END IF
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END IF
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IF( AIMAG( X( IX ) ).NE.ZERO ) THEN
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TEMP1 = ABS( AIMAG( X( IX ) ) )
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IF( SCALE.LT.TEMP1 ) THEN
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SUMSQ = 1 + SUMSQ*( SCALE / TEMP1 )**2
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SCALE = TEMP1
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ELSE
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SUMSQ = SUMSQ + ( TEMP1 / SCALE )**2
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END IF
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END IF
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10 CONTINUE
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END IF
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*
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RETURN
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*
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* End of CLASSQ
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*
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END
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