*> \brief \b ICMAX1 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 ICMAX1 + dependencies *> *> [TGZ] *> *> [ZIP] *> *> [TXT] *> \endhtmlonly * * Definition: * =========== * * INTEGER FUNCTION ICMAX1( N, CX, INCX ) * * .. Scalar Arguments .. * INTEGER INCX, N * .. * .. Array Arguments .. * COMPLEX CX( * ) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> ICMAX1 finds the index of the first vector element of maximum absolute value. *> *> Based on ICAMAX 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 CX. *> \endverbatim *> *> \param[in] CX *> \verbatim *> CX is COMPLEX array, dimension (N) *> The vector CX. The ICMAX1 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 CX. INCX >= 1. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup complexOTHERauxiliary * *> \par Contributors: * ================== *> *> Nick Higham for use with CLACON. * * ===================================================================== INTEGER FUNCTION ICMAX1( N, CX, INCX ) * * -- LAPACK auxiliary routine -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. INTEGER INCX, N * .. * .. Array Arguments .. COMPLEX CX(*) * .. * * ===================================================================== * * .. Local Scalars .. REAL SMAX INTEGER I, IX * .. * .. Intrinsic Functions .. INTRINSIC ABS * .. * .. Executable Statements .. * ICMAX1 = 0 IF (N.LT.1 .OR. INCX.LE.0) RETURN ICMAX1 = 1 IF (N.EQ.1) RETURN IF (INCX.EQ.1) THEN * * code for increment equal to 1 * SMAX = ABS(CX(1)) DO I = 2,N IF (ABS(CX(I)).GT.SMAX) THEN ICMAX1 = I SMAX = ABS(CX(I)) END IF END DO ELSE * * code for increment not equal to 1 * IX = 1 SMAX = ABS(CX(1)) IX = IX + INCX DO I = 2,N IF (ABS(CX(IX)).GT.SMAX) THEN ICMAX1 = I SMAX = ABS(CX(IX)) END IF IX = IX + INCX END DO END IF RETURN * * End of ICMAX1 * END