integer function isamax	(	integer	N,
		real, dimension(*)	SX,
		integer	INCX
	)

ISAMAX

Purpose:

    ISAMAX finds the index of the first element having maximum absolute value.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date

December 2016

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(*)

Definition at line 53 of file isamax.f.

*
*  -- Reference BLAS level1 routine (version 3.7.0) --
*  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER incx,n
*     ..
*     .. Array Arguments ..
      REAL sx(*)
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      REAL smax
      INTEGER i,ix
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC abs
*     ..
      isamax = 0
      IF (n.LT.1 .OR. incx.LE.0) RETURN
      isamax = 1
      IF (n.EQ.1) RETURN
      IF (incx.EQ.1) THEN
*
*        code for increment equal to 1
*
         smax = abs(sx(1))
         DO i = 2,n
            IF (abs(sx(i)).GT.smax) THEN
               isamax = i
               smax = abs(sx(i))
            END IF
         END DO
      ELSE
*
*        code for increment not equal to 1
*
         ix = 1
         smax = abs(sx(1))
         ix = ix + incx
         DO i = 2,n
            IF (abs(sx(ix)).GT.smax) THEN
               isamax = i
               smax = abs(sx(ix))
            END IF
            ix = ix + incx
         END DO
      END IF
      RETURN

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