integer function idamax	(	integer	N,
		double precision, dimension(*)	DX,
		integer	INCX
	)

IDAMAX

Purpose:

    IDAMAX 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 idamax.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 ..
      DOUBLE PRECISION dx(*)
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      DOUBLE PRECISION dmax
      INTEGER i,ix
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC dabs
*     ..
      idamax = 0
      IF (n.LT.1 .OR. incx.LE.0) RETURN
      idamax = 1
      IF (n.EQ.1) RETURN
      IF (incx.EQ.1) THEN
*
*        code for increment equal to 1
*
         dmax = dabs(dx(1))
         DO i = 2,n
            IF (dabs(dx(i)).GT.dmax) THEN
               idamax = i
               dmax = dabs(dx(i))
            END IF
         END DO
      ELSE
*
*        code for increment not equal to 1
*
         ix = 1
         dmax = dabs(dx(1))
         ix = ix + incx
         DO i = 2,n
            IF (dabs(dx(ix)).GT.dmax) THEN
               idamax = i
               dmax = dabs(dx(ix))
            END IF
            ix = ix + incx
         END DO
      END IF
      RETURN

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