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version 1.7, 2010/12/21 13:53:41
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version 1.17, 2017/06/17 10:54:07
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| INTEGER FUNCTION IZMAX1( N, CX, INCX ) |
*> \brief \b IZMAX1 finds the index of the first vector element of maximum absolute value. |
| * |
* |
| * -- LAPACK auxiliary routine (version 3.2) -- |
* =========== DOCUMENTATION =========== |
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* |
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* Online html documentation available at |
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* http://www.netlib.org/lapack/explore-html/ |
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* |
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*> \htmlonly |
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*> Download IZMAX1 + dependencies |
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/izmax1.f"> |
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*> [TGZ]</a> |
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/izmax1.f"> |
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*> [ZIP]</a> |
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/izmax1.f"> |
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*> [TXT]</a> |
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*> \endhtmlonly |
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* |
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* Definition: |
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* =========== |
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* |
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* INTEGER FUNCTION IZMAX1( N, ZX, INCX ) |
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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 ZX( * ) |
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* .. |
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* |
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* |
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*> \par Purpose: |
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* ============= |
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*> |
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*> \verbatim |
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*> |
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*> IZMAX1 finds the index of the first vector element of maximum absolute value. |
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*> |
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*> Based on IZAMAX from Level 1 BLAS. |
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*> The change is to use the 'genuine' absolute value. |
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*> \endverbatim |
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* |
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* Arguments: |
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* ========== |
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* |
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*> \param[in] N |
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*> \verbatim |
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*> N is INTEGER |
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*> The number of elements in the vector ZX. |
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*> \endverbatim |
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*> |
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*> \param[in] ZX |
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*> \verbatim |
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*> ZX is COMPLEX*16 array, dimension (N) |
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*> The vector ZX. The IZMAX1 function returns the index of its first |
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*> element of maximum absolute value. |
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*> \endverbatim |
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*> |
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*> \param[in] INCX |
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*> \verbatim |
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*> INCX is INTEGER |
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*> The spacing between successive values of ZX. INCX >= 1. |
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*> \endverbatim |
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* |
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* Authors: |
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* ======== |
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* |
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*> \author Univ. of Tennessee |
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*> \author Univ. of California Berkeley |
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*> \author Univ. of Colorado Denver |
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*> \author NAG Ltd. |
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* |
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*> \date February 2014 |
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* |
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*> \ingroup complexOTHERauxiliary |
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* |
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*> \par Contributors: |
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* ================== |
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*> |
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*> Nick Higham for use with ZLACON. |
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* |
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* ===================================================================== |
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INTEGER FUNCTION IZMAX1( N, ZX, INCX ) |
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* |
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* -- LAPACK auxiliary routine (version 3.7.0) -- |
| * -- 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..-- |
| * November 2006 |
* February 2014 |
| * |
* |
| * .. Scalar Arguments .. |
* .. Scalar Arguments .. |
| INTEGER INCX, N |
INTEGER INCX, N |
| * .. |
* .. |
| * .. Array Arguments .. |
* .. Array Arguments .. |
| COMPLEX*16 CX( * ) |
COMPLEX*16 ZX(*) |
| * .. |
* .. |
| * |
* |
| * Purpose |
* ===================================================================== |
| * ======= |
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| * |
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| * IZMAX1 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 IZAMAX 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 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 >= 1. |
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| * |
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| * ===================================================================== |
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| * |
* |
| * .. 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 |
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