--- rpl/lapack/blas/idamax.f 2010/01/26 15:22:45 1.1.1.1 +++ rpl/lapack/blas/idamax.f 2016/08/27 15:37:53 1.13 @@ -1,4 +1,61 @@ +*> \brief \b IDAMAX +* +* =========== DOCUMENTATION =========== +* +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +* Definition: +* =========== +* +* INTEGER FUNCTION IDAMAX(N,DX,INCX) +* +* .. Scalar Arguments .. +* INTEGER INCX,N +* .. +* .. Array Arguments .. +* DOUBLE PRECISION DX(*) +* .. +* +* +*> \par Purpose: +* ============= +*> +*> \verbatim +*> +*> IDAMAX finds the index of the first element having maximum absolute value. +*> \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, linpack, 3/11/78. +*> modified 3/93 to return if incx .le. 0. +*> modified 12/3/93, array(1) declarations changed to array(*) +*> \endverbatim +*> +* ===================================================================== INTEGER FUNCTION IDAMAX(N,DX,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 * .. @@ -6,18 +63,6 @@ DOUBLE PRECISION DX(*) * .. * -* Purpose -* ======= -* -* IDAMAX finds the index of element having max. absolute value. -* -* Further Details -* =============== -* -* jack dongarra, linpack, 3/11/78. -* modified 3/93 to return if incx .le. 0. -* modified 12/3/93, array(1) declarations changed to array(*) -* * ===================================================================== * * .. Local Scalars .. @@ -31,28 +76,31 @@ IF (N.LT.1 .OR. INCX.LE.0) RETURN IDAMAX = 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 - DMAX = DABS(DX(1)) - IX = IX + INCX - DO 10 I = 2,N - IF (DABS(DX(IX)).LE.DMAX) GO TO 5 - IDAMAX = I - DMAX = DABS(DX(IX)) - 5 IX = IX + INCX - 10 CONTINUE - RETURN + DMAX = DABS(DX(1)) + DO I = 2,N + IF (DABS(DX(I)).GT.DMAX) THEN + IDAMAX = I + DMAX = DABS(DX(I)) + END IF + END DO + ELSE * -* code for increment equal to 1 +* code for increment not equal to 1 * - 20 DMAX = DABS(DX(1)) - DO 30 I = 2,N - IF (DABS(DX(I)).LE.DMAX) GO TO 30 - IDAMAX = I - DMAX = DABS(DX(I)) - 30 CONTINUE + IX = 1 + DMAX = DABS(DX(1)) + IX = IX + INCX + DO I = 2,N + IF (DABS(DX(IX)).GT.DMAX) THEN + IDAMAX = I + DMAX = DABS(DX(IX)) + END IF + IX = IX + INCX + END DO + END IF RETURN END