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Annotation of rpl/lapack/lapack/izmax1.f, revision 1.4

1.1       bertrand    1:       INTEGER          FUNCTION IZMAX1( N, CX, INCX )
                      2: *
                      3: *  -- LAPACK auxiliary routine (version 3.2) --
                      4: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                      5: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
                      6: *     November 2006
                      7: *
                      8: *     .. Scalar Arguments ..
                      9:       INTEGER            INCX, N
                     10: *     ..
                     11: *     .. Array Arguments ..
                     12:       COMPLEX*16         CX( * )
                     13: *     ..
                     14: *
                     15: *  Purpose
                     16: *  =======
                     17: *
                     18: *  IZMAX1 finds the index of the element whose real part has maximum
                     19: *  absolute value.
                     20: *
                     21: *  Based on IZAMAX from Level 1 BLAS.
                     22: *  The change is to use the 'genuine' absolute value.
                     23: *
                     24: *  Contributed by Nick Higham for use with ZLACON.
                     25: *
                     26: *  Arguments
                     27: *  =========
                     28: *
                     29: *  N       (input) INTEGER
                     30: *          The number of elements in the vector CX.
                     31: *
                     32: *  CX      (input) COMPLEX*16 array, dimension (N)
                     33: *          The vector whose elements will be summed.
                     34: *
                     35: *  INCX    (input) INTEGER
                     36: *          The spacing between successive values of CX.  INCX >= 1.
                     37: *
                     38: * =====================================================================
                     39: *
                     40: *     .. Local Scalars ..
                     41:       INTEGER            I, IX
                     42:       DOUBLE PRECISION   SMAX
                     43:       COMPLEX*16         ZDUM
                     44: *     ..
                     45: *     .. Intrinsic Functions ..
                     46:       INTRINSIC          ABS
                     47: *     ..
                     48: *     .. Statement Functions ..
                     49:       DOUBLE PRECISION   CABS1
                     50: *     ..
                     51: *     .. Statement Function definitions ..
                     52: *
                     53: *     NEXT LINE IS THE ONLY MODIFICATION.
                     54:       CABS1( ZDUM ) = ABS( ZDUM )
                     55: *     ..
                     56: *     .. Executable Statements ..
                     57: *
                     58:       IZMAX1 = 0
                     59:       IF( N.LT.1 )
                     60:      $   RETURN
                     61:       IZMAX1 = 1
                     62:       IF( N.EQ.1 )
                     63:      $   RETURN
                     64:       IF( INCX.EQ.1 )
                     65:      $   GO TO 30
                     66: *
                     67: *     CODE FOR INCREMENT NOT EQUAL TO 1
                     68: *
                     69:       IX = 1
                     70:       SMAX = CABS1( CX( 1 ) )
                     71:       IX = IX + INCX
                     72:       DO 20 I = 2, N
                     73:          IF( CABS1( CX( IX ) ).LE.SMAX )
                     74:      $      GO TO 10
                     75:          IZMAX1 = I
                     76:          SMAX = CABS1( CX( IX ) )
                     77:    10    CONTINUE
                     78:          IX = IX + INCX
                     79:    20 CONTINUE
                     80:       RETURN
                     81: *
                     82: *     CODE FOR INCREMENT EQUAL TO 1
                     83: *
                     84:    30 CONTINUE
                     85:       SMAX = CABS1( CX( 1 ) )
                     86:       DO 40 I = 2, N
                     87:          IF( CABS1( CX( I ) ).LE.SMAX )
                     88:      $      GO TO 40
                     89:          IZMAX1 = I
                     90:          SMAX = CABS1( CX( I ) )
                     91:    40 CONTINUE
                     92:       RETURN
                     93: *
                     94: *     End of IZMAX1
                     95: *
                     96:       END