version 1.2, 2010/04/21 13:45:10
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version 1.11, 2014/01/27 09:28:13
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*> \brief \b IZAMAX |
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* |
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* =========== 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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* Definition: |
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* =========== |
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* |
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* INTEGER FUNCTION IZAMAX(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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*> IZAMAX finds the index of element having max. absolute value. |
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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 November 2011 |
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* |
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*> \ingroup aux_blas |
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* |
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*> \par Further Details: |
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* ===================== |
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*> |
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*> \verbatim |
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*> |
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*> jack dongarra, 1/15/85. |
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*> modified 3/93 to return if incx .le. 0. |
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*> modified 12/3/93, array(1) declarations changed to array(*) |
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*> \endverbatim |
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*> |
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* ===================================================================== |
INTEGER FUNCTION IZAMAX(N,ZX,INCX) |
INTEGER FUNCTION IZAMAX(N,ZX,INCX) |
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* |
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* -- Reference BLAS level1 routine (version 3.4.0) -- |
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* -- Reference BLAS 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 2011 |
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* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
INTEGER INCX,N |
INTEGER INCX,N |
* .. |
* .. |
* .. Array Arguments .. |
* .. Array Arguments .. |
DOUBLE COMPLEX ZX(*) |
COMPLEX*16 ZX(*) |
* .. |
* .. |
* |
* |
* Purpose |
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* ======= |
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* |
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* IZAMAX finds the index of element having max. absolute value. |
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* |
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* Further Details |
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* =============== |
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* |
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* jack dongarra, 1/15/85. |
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* modified 3/93 to return if incx .le. 0. |
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* modified 12/3/93, array(1) declarations changed to array(*) |
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* |
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* ===================================================================== |
* ===================================================================== |
* |
* |
* .. Local Scalars .. |
* .. Local Scalars .. |
DOUBLE PRECISION SMAX |
DOUBLE PRECISION DMAX |
INTEGER I,IX |
INTEGER I,IX |
* .. |
* .. |
* .. External Functions .. |
* .. External Functions .. |
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IF (N.LT.1 .OR. INCX.LE.0) RETURN |
IF (N.LT.1 .OR. INCX.LE.0) RETURN |
IZAMAX = 1 |
IZAMAX = 1 |
IF (N.EQ.1) RETURN |
IF (N.EQ.1) RETURN |
IF (INCX.EQ.1) GO TO 20 |
IF (INCX.EQ.1) THEN |
* |
* |
* code for increment not equal to 1 |
* code for increment equal to 1 |
* |
* |
IX = 1 |
DMAX = DCABS1(ZX(1)) |
SMAX = DCABS1(ZX(1)) |
DO I = 2,N |
IX = IX + INCX |
IF (DCABS1(ZX(I)).GT.DMAX) THEN |
DO 10 I = 2,N |
IZAMAX = I |
IF (DCABS1(ZX(IX)).LE.SMAX) GO TO 5 |
DMAX = DCABS1(ZX(I)) |
IZAMAX = I |
END IF |
SMAX = DCABS1(ZX(IX)) |
END DO |
5 IX = IX + INCX |
ELSE |
10 CONTINUE |
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RETURN |
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* |
* |
* code for increment equal to 1 |
* code for increment not equal to 1 |
* |
* |
20 SMAX = DCABS1(ZX(1)) |
IX = 1 |
DO 30 I = 2,N |
DMAX = DCABS1(ZX(1)) |
IF (DCABS1(ZX(I)).LE.SMAX) GO TO 30 |
IX = IX + INCX |
IZAMAX = I |
DO I = 2,N |
SMAX = DCABS1(ZX(I)) |
IF (DCABS1(ZX(IX)).GT.DMAX) THEN |
30 CONTINUE |
IZAMAX = I |
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DMAX = DCABS1(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 |
END |