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    1: *> \brief \b IZMAX1
    2: *
    3: *  =========== DOCUMENTATION ===========
    4: *
    5: * Online html documentation available at 
    6: *            http://www.netlib.org/lapack/explore-html/ 
    7: *
    8: *> \htmlonly
    9: *> Download IZMAX1 + dependencies 
   10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/izmax1.f"> 
   11: *> [TGZ]</a> 
   12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/izmax1.f"> 
   13: *> [ZIP]</a> 
   14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/izmax1.f"> 
   15: *> [TXT]</a>
   16: *> \endhtmlonly 
   17: *
   18: *  Definition:
   19: *  ===========
   20: *
   21: *       INTEGER          FUNCTION IZMAX1( N, CX, INCX )
   22: * 
   23: *       .. Scalar Arguments ..
   24: *       INTEGER            INCX, N
   25: *       ..
   26: *       .. Array Arguments ..
   27: *       COMPLEX*16         CX( * )
   28: *       ..
   29: *  
   30: *
   31: *> \par Purpose:
   32: *  =============
   33: *>
   34: *> \verbatim
   35: *>
   36: *> IZMAX1 finds the index of the element whose real part has maximum
   37: *> absolute value.
   38: *>
   39: *> Based on IZAMAX from Level 1 BLAS.
   40: *> The change is to use the 'genuine' absolute value.
   41: *> \endverbatim
   42: *
   43: *  Arguments:
   44: *  ==========
   45: *
   46: *> \param[in] N
   47: *> \verbatim
   48: *>          N is INTEGER
   49: *>          The number of elements in the vector CX.
   50: *> \endverbatim
   51: *>
   52: *> \param[in] CX
   53: *> \verbatim
   54: *>          CX is COMPLEX*16 array, dimension (N)
   55: *>          The vector whose elements will be summed.
   56: *> \endverbatim
   57: *>
   58: *> \param[in] INCX
   59: *> \verbatim
   60: *>          INCX is INTEGER
   61: *>          The spacing between successive values of CX.  INCX >= 1.
   62: *> \endverbatim
   63: *
   64: *  Authors:
   65: *  ========
   66: *
   67: *> \author Univ. of Tennessee 
   68: *> \author Univ. of California Berkeley 
   69: *> \author Univ. of Colorado Denver 
   70: *> \author NAG Ltd. 
   71: *
   72: *> \date November 2011
   73: *
   74: *> \ingroup complex16OTHERauxiliary
   75: *
   76: *> \par Contributors:
   77: *  ==================
   78: *>
   79: *> Nick Higham for use with ZLACON.
   80: *
   81: *  =====================================================================
   82:       INTEGER          FUNCTION IZMAX1( N, CX, INCX )
   83: *
   84: *  -- LAPACK auxiliary routine (version 3.4.0) --
   85: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
   86: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
   87: *     November 2011
   88: *
   89: *     .. Scalar Arguments ..
   90:       INTEGER            INCX, N
   91: *     ..
   92: *     .. Array Arguments ..
   93:       COMPLEX*16         CX( * )
   94: *     ..
   95: *
   96: * =====================================================================
   97: *
   98: *     .. Local Scalars ..
   99:       INTEGER            I, IX
  100:       DOUBLE PRECISION   SMAX
  101:       COMPLEX*16         ZDUM
  102: *     ..
  103: *     .. Intrinsic Functions ..
  104:       INTRINSIC          ABS
  105: *     ..
  106: *     .. Statement Functions ..
  107:       DOUBLE PRECISION   CABS1
  108: *     ..
  109: *     .. Statement Function definitions ..
  110: *
  111: *     NEXT LINE IS THE ONLY MODIFICATION.
  112:       CABS1( ZDUM ) = ABS( ZDUM )
  113: *     ..
  114: *     .. Executable Statements ..
  115: *
  116:       IZMAX1 = 0
  117:       IF( N.LT.1 )
  118:      $   RETURN
  119:       IZMAX1 = 1
  120:       IF( N.EQ.1 )
  121:      $   RETURN
  122:       IF( INCX.EQ.1 )
  123:      $   GO TO 30
  124: *
  125: *     CODE FOR INCREMENT NOT EQUAL TO 1
  126: *
  127:       IX = 1
  128:       SMAX = CABS1( CX( 1 ) )
  129:       IX = IX + INCX
  130:       DO 20 I = 2, N
  131:          IF( CABS1( CX( IX ) ).LE.SMAX )
  132:      $      GO TO 10
  133:          IZMAX1 = I
  134:          SMAX = CABS1( CX( IX ) )
  135:    10    CONTINUE
  136:          IX = IX + INCX
  137:    20 CONTINUE
  138:       RETURN
  139: *
  140: *     CODE FOR INCREMENT EQUAL TO 1
  141: *
  142:    30 CONTINUE
  143:       SMAX = CABS1( CX( 1 ) )
  144:       DO 40 I = 2, N
  145:          IF( CABS1( CX( I ) ).LE.SMAX )
  146:      $      GO TO 40
  147:          IZMAX1 = I
  148:          SMAX = CABS1( CX( I ) )
  149:    40 CONTINUE
  150:       RETURN
  151: *
  152: *     End of IZMAX1
  153: *
  154:       END