--- rpl/lapack/blas/izamax.f 2010/08/07 13:22:10 1.4 +++ rpl/lapack/blas/izamax.f 2015/11/26 11:44:14 1.12 @@ -1,27 +1,72 @@ +*> \brief \b IZAMAX +* +* =========== DOCUMENTATION =========== +* +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +* Definition: +* =========== +* +* INTEGER FUNCTION IZAMAX(N,ZX,INCX) +* +* .. Scalar Arguments .. +* INTEGER INCX,N +* .. +* .. Array Arguments .. +* COMPLEX*16 ZX(*) +* .. +* +* +*> \par Purpose: +* ============= +*> +*> \verbatim +*> +*> IZAMAX finds the index of the first element having maximum |Re(.)| + |Im(.)| +*> \endverbatim +* +* Authors: +* ======== +* +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. +* +*> \date November 2015 +* +*> \ingroup aux_blas +* +*> \par Further Details: +* ===================== +*> +*> \verbatim +*> +*> jack dongarra, 1/15/85. +*> modified 3/93 to return if incx .le. 0. +*> modified 12/3/93, array(1) declarations changed to array(*) +*> \endverbatim +*> +* ===================================================================== INTEGER FUNCTION IZAMAX(N,ZX,INCX) +* +* -- Reference BLAS level1 routine (version 3.6.0) -- +* -- Reference BLAS is a software package provided by Univ. of Tennessee, -- +* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- +* November 2015 +* * .. Scalar Arguments .. INTEGER INCX,N * .. * .. Array Arguments .. - DOUBLE COMPLEX ZX(*) + COMPLEX*16 ZX(*) * .. * -* Purpose -* ======= -* -* IZAMAX finds the index of element having max. absolute value. -* -* Further Details -* =============== -* -* jack dongarra, 1/15/85. -* modified 3/93 to return if incx .le. 0. -* modified 12/3/93, array(1) declarations changed to array(*) -* * ===================================================================== * * .. Local Scalars .. - DOUBLE PRECISION SMAX + DOUBLE PRECISION DMAX INTEGER I,IX * .. * .. External Functions .. @@ -32,28 +77,31 @@ IF (N.LT.1 .OR. INCX.LE.0) RETURN IZAMAX = 1 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 - SMAX = DCABS1(ZX(1)) - IX = IX + INCX - DO 10 I = 2,N - IF (DCABS1(ZX(IX)).LE.SMAX) GO TO 5 - IZAMAX = I - SMAX = DCABS1(ZX(IX)) - 5 IX = IX + INCX - 10 CONTINUE - RETURN + DMAX = DCABS1(ZX(1)) + DO I = 2,N + IF (DCABS1(ZX(I)).GT.DMAX) THEN + IZAMAX = I + DMAX = DCABS1(ZX(I)) + END IF + END DO + ELSE * -* code for increment equal to 1 +* code for increment not equal to 1 * - 20 SMAX = DCABS1(ZX(1)) - DO 30 I = 2,N - IF (DCABS1(ZX(I)).LE.SMAX) GO TO 30 - IZAMAX = I - SMAX = DCABS1(ZX(I)) - 30 CONTINUE + IX = 1 + DMAX = DCABS1(ZX(1)) + IX = IX + INCX + DO I = 2,N + IF (DCABS1(ZX(IX)).GT.DMAX) THEN + IZAMAX = I + DMAX = DCABS1(ZX(IX)) + END IF + IX = IX + INCX + END DO + END IF RETURN END