*> \brief \b IZMAX1 finds the index of the first vector element of maximum absolute value. * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * *> \htmlonly *> Download IZMAX1 + dependencies *> *> [TGZ] *> *> [ZIP] *> *> [TXT] *> \endhtmlonly * * Definition: * =========== * * INTEGER FUNCTION IZMAX1( N, ZX, INCX ) * * .. Scalar Arguments .. * INTEGER INCX, N * .. * .. Array Arguments .. * COMPLEX*16 ZX( * ) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> IZMAX1 finds the index of the first vector element of maximum absolute value. *> *> Based on IZAMAX from Level 1 BLAS. *> The change is to use the 'genuine' absolute value. *> \endverbatim * * Arguments: * ========== * *> \param[in] N *> \verbatim *> N is INTEGER *> The number of elements in the vector ZX. *> \endverbatim *> *> \param[in] ZX *> \verbatim *> ZX is COMPLEX*16 array, dimension (N) *> The vector ZX. The IZMAX1 function returns the index of its first *> element of maximum absolute value. *> \endverbatim *> *> \param[in] INCX *> \verbatim *> INCX is INTEGER *> The spacing between successive values of ZX. INCX >= 1. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \date February 2014 * *> \ingroup complexOTHERauxiliary * *> \par Contributors: * ================== *> *> Nick Higham for use with ZLACON. * * ===================================================================== INTEGER FUNCTION IZMAX1( N, ZX, INCX ) * * -- LAPACK auxiliary routine (version 3.7.0) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * February 2014 * * .. Scalar Arguments .. INTEGER INCX, N * .. * .. Array Arguments .. COMPLEX*16 ZX(*) * .. * * ===================================================================== * * .. Local Scalars .. DOUBLE PRECISION DMAX INTEGER I, IX * .. * .. Intrinsic Functions .. INTRINSIC ABS * .. * .. Executable Statements .. * IZMAX1 = 0 IF (N.LT.1 .OR. INCX.LE.0) RETURN IZMAX1 = 1 IF (N.EQ.1) RETURN IF (INCX.EQ.1) THEN * * code for increment equal to 1 * DMAX = ABS(ZX(1)) DO I = 2,N IF (ABS(ZX(I)).GT.DMAX) THEN IZMAX1 = I DMAX = ABS(ZX(I)) END IF END DO ELSE * * code for increment not equal to 1 * IX = 1 DMAX = ABS(ZX(1)) IX = IX + INCX DO I = 2,N IF (ABS(ZX(IX)).GT.DMAX) THEN IZMAX1 = I DMAX = ABS(ZX(IX)) END IF IX = IX + INCX END DO END IF RETURN * * End of IZMAX1 * END