82 lines
1.7 KiB
FortranFixed
82 lines
1.7 KiB
FortranFixed
DOUBLE PRECISION FUNCTION DZSUM1( N, CX, INCX )
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*
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* -- LAPACK auxiliary routine (version 3.1) --
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* Univ. of Tennessee, Univ. of California Berkeley 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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* ..
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* .. Array Arguments ..
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COMPLEX*16 CX( * )
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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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* DZSUM1 takes the sum of the absolute values of a complex
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* vector and returns a double precision result.
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*
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* Based on DZASUM from the Level 1 BLAS.
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* The change is to use the 'genuine' absolute value.
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*
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* Contributed by Nick Higham for use with ZLACON.
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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 in the vector CX.
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*
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* CX (input) COMPLEX*16 array, dimension (N)
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* The vector whose elements will be summed.
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*
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* INCX (input) INTEGER
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* The spacing between successive values of CX. INCX > 0.
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*
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* =====================================================================
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*
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* .. Local Scalars ..
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INTEGER I, NINCX
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DOUBLE PRECISION STEMP
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC ABS
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* ..
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* .. Executable Statements ..
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*
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DZSUM1 = 0.0D0
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STEMP = 0.0D0
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IF( N.LE.0 )
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$ RETURN
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IF( INCX.EQ.1 )
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$ GO TO 20
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*
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* CODE FOR INCREMENT NOT EQUAL TO 1
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*
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NINCX = N*INCX
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DO 10 I = 1, NINCX, INCX
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*
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* NEXT LINE MODIFIED.
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*
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STEMP = STEMP + ABS( CX( I ) )
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10 CONTINUE
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DZSUM1 = STEMP
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RETURN
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*
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* CODE FOR INCREMENT EQUAL TO 1
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*
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20 CONTINUE
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DO 30 I = 1, N
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*
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* NEXT LINE MODIFIED.
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*
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STEMP = STEMP + ABS( CX( I ) )
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30 CONTINUE
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DZSUM1 = STEMP
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RETURN
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*
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* End of DZSUM1
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*
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END
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