96 lines
2.1 KiB
FortranFixed
96 lines
2.1 KiB
FortranFixed
INTEGER FUNCTION ICMAX1( 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 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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* ICMAX1 finds the index of the element whose real part has maximum
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* absolute value.
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*
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* Based on ICAMAX from 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 CLACON.
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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 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 >= 1.
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*
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* =====================================================================
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*
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* .. Local Scalars ..
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INTEGER I, IX
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REAL SMAX
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COMPLEX ZDUM
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC ABS
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* ..
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* .. Statement Functions ..
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REAL CABS1
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* ..
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* .. Statement Function definitions ..
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*
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* NEXT LINE IS THE ONLY MODIFICATION.
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CABS1( ZDUM ) = ABS( ZDUM )
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* ..
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* .. Executable Statements ..
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*
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ICMAX1 = 0
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IF( N.LT.1 )
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$ RETURN
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ICMAX1 = 1
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IF( N.EQ.1 )
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$ RETURN
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IF( INCX.EQ.1 )
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$ GO TO 30
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*
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* CODE FOR INCREMENT NOT EQUAL TO 1
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*
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IX = 1
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SMAX = CABS1( CX( 1 ) )
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IX = IX + INCX
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DO 20 I = 2, N
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IF( CABS1( CX( IX ) ).LE.SMAX )
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$ GO TO 10
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ICMAX1 = I
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SMAX = CABS1( CX( IX ) )
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10 CONTINUE
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IX = IX + INCX
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20 CONTINUE
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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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30 CONTINUE
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SMAX = CABS1( CX( 1 ) )
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DO 40 I = 2, N
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IF( CABS1( CX( I ) ).LE.SMAX )
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$ GO TO 40
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ICMAX1 = I
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SMAX = CABS1( CX( I ) )
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40 CONTINUE
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RETURN
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*
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* End of ICMAX1
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*
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END
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