version 1.12, 2012/12/14 12:30:28
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version 1.15, 2015/11/26 11:44:21
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*> \brief \b IZMAX1 finds the index of the vector element whose real part has maximum absolute value. |
*> \brief \b IZMAX1 finds the index of the first vector element of maximum absolute value. |
* |
* |
* =========== DOCUMENTATION =========== |
* =========== DOCUMENTATION =========== |
* |
* |
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* Definition: |
* Definition: |
* =========== |
* =========== |
* |
* |
* INTEGER FUNCTION IZMAX1( N, CX, INCX ) |
* INTEGER FUNCTION IZMAX1( N, ZX, INCX ) |
* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
* INTEGER INCX, N |
* INTEGER INCX, N |
* .. |
* .. |
* .. Array Arguments .. |
* .. Array Arguments .. |
* COMPLEX*16 CX( * ) |
* COMPLEX*16 ZX( * ) |
* .. |
* .. |
* |
* |
* |
* |
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*> |
*> |
*> \verbatim |
*> \verbatim |
*> |
*> |
*> IZMAX1 finds the index of the element whose real part has maximum |
*> IZMAX1 finds the index of the first vector element of maximum absolute value. |
*> absolute value. |
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*> |
*> |
*> Based on IZAMAX from Level 1 BLAS. |
*> Based on IZAMAX from Level 1 BLAS. |
*> The change is to use the 'genuine' absolute value. |
*> The change is to use the 'genuine' absolute value. |
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*> \param[in] N |
*> \param[in] N |
*> \verbatim |
*> \verbatim |
*> N is INTEGER |
*> N is INTEGER |
*> The number of elements in the vector CX. |
*> The number of elements in the vector ZX. |
*> \endverbatim |
*> \endverbatim |
*> |
*> |
*> \param[in] CX |
*> \param[in] ZX |
*> \verbatim |
*> \verbatim |
*> CX is COMPLEX*16 array, dimension (N) |
*> ZX is COMPLEX*16 array, dimension (N) |
*> The vector whose elements will be summed. |
*> The vector ZX. The IZMAX1 function returns the index of its first |
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*> element of maximum absolute value. |
*> \endverbatim |
*> \endverbatim |
*> |
*> |
*> \param[in] INCX |
*> \param[in] INCX |
*> \verbatim |
*> \verbatim |
*> INCX is INTEGER |
*> INCX is INTEGER |
*> The spacing between successive values of CX. INCX >= 1. |
*> The spacing between successive values of ZX. INCX >= 1. |
*> \endverbatim |
*> \endverbatim |
* |
* |
* Authors: |
* Authors: |
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*> \author Univ. of Colorado Denver |
*> \author Univ. of Colorado Denver |
*> \author NAG Ltd. |
*> \author NAG Ltd. |
* |
* |
*> \date September 2012 |
*> \date February 2014 |
* |
* |
*> \ingroup complex16OTHERauxiliary |
*> \ingroup complexOTHERauxiliary |
* |
* |
*> \par Contributors: |
*> \par Contributors: |
* ================== |
* ================== |
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*> Nick Higham for use with ZLACON. |
*> Nick Higham for use with ZLACON. |
* |
* |
* ===================================================================== |
* ===================================================================== |
INTEGER FUNCTION IZMAX1( N, CX, INCX ) |
INTEGER FUNCTION IZMAX1( N, ZX, INCX ) |
* |
* |
* -- LAPACK auxiliary routine (version 3.4.2) -- |
* -- LAPACK auxiliary routine (version 3.6.0) -- |
* -- LAPACK is a software package provided by Univ. of Tennessee, -- |
* -- LAPACK is a software package provided by Univ. of Tennessee, -- |
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
* September 2012 |
* February 2014 |
* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
INTEGER INCX, N |
INTEGER INCX, N |
* .. |
* .. |
* .. Array Arguments .. |
* .. Array Arguments .. |
COMPLEX*16 CX( * ) |
COMPLEX*16 ZX(*) |
* .. |
* .. |
* |
* |
* ===================================================================== |
* ===================================================================== |
* |
* |
* .. Local Scalars .. |
* .. Local Scalars .. |
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DOUBLE PRECISION DMAX |
INTEGER I, IX |
INTEGER I, IX |
DOUBLE PRECISION SMAX |
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COMPLEX*16 ZDUM |
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* .. |
* .. |
* .. Intrinsic Functions .. |
* .. Intrinsic Functions .. |
INTRINSIC ABS |
INTRINSIC ABS |
* .. |
* .. |
* .. Statement Functions .. |
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DOUBLE PRECISION 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 .. |
* .. Executable Statements .. |
* |
* |
IZMAX1 = 0 |
IZMAX1 = 0 |
IF( N.LT.1 ) |
IF (N.LT.1 .OR. INCX.LE.0) RETURN |
$ RETURN |
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IZMAX1 = 1 |
IZMAX1 = 1 |
IF( N.EQ.1 ) |
IF (N.EQ.1) RETURN |
$ RETURN |
IF (INCX.EQ.1) THEN |
IF( INCX.EQ.1 ) |
* |
$ GO TO 30 |
* code for increment equal to 1 |
* |
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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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IZMAX1 = 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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* |
* |
* CODE FOR INCREMENT EQUAL TO 1 |
DMAX = ABS(ZX(1)) |
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DO I = 2,N |
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IF (ABS(ZX(I)).GT.DMAX) THEN |
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IZMAX1 = I |
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DMAX = ABS(ZX(I)) |
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END IF |
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END DO |
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ELSE |
* |
* |
30 CONTINUE |
* code for increment not equal to 1 |
SMAX = CABS1( CX( 1 ) ) |
* |
DO 40 I = 2, N |
IX = 1 |
IF( CABS1( CX( I ) ).LE.SMAX ) |
DMAX = ABS(ZX(1)) |
$ GO TO 40 |
IX = IX + INCX |
IZMAX1 = I |
DO I = 2,N |
SMAX = CABS1( CX( I ) ) |
IF (ABS(ZX(IX)).GT.DMAX) THEN |
40 CONTINUE |
IZMAX1 = I |
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DMAX = ABS(ZX(IX)) |
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END IF |
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IX = IX + INCX |
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END DO |
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END IF |
RETURN |
RETURN |
* |
* |
* End of IZMAX1 |
* End of IZMAX1 |