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    1:       INTEGER FUNCTION IDAMAX(N,DX,INCX)
    2: *     .. Scalar Arguments ..
    3:       INTEGER INCX,N
    4: *     ..
    5: *     .. Array Arguments ..
    6:       DOUBLE PRECISION DX(*)
    7: *     ..
    8: *
    9: *  Purpose
   10: *  =======
   11: *
   12: *     IDAMAX finds the index of element having max. absolute value.
   13: *
   14: *  Further Details
   15: *  ===============
   16: *
   17: *     jack dongarra, linpack, 3/11/78.
   18: *     modified 3/93 to return if incx .le. 0.
   19: *     modified 12/3/93, array(1) declarations changed to array(*)
   20: *
   21: *  =====================================================================
   22: *
   23: *     .. Local Scalars ..
   24:       DOUBLE PRECISION DMAX
   25:       INTEGER I,IX
   26: *     ..
   27: *     .. Intrinsic Functions ..
   28:       INTRINSIC DABS
   29: *     ..
   30:       IDAMAX = 0
   31:       IF (N.LT.1 .OR. INCX.LE.0) RETURN
   32:       IDAMAX = 1
   33:       IF (N.EQ.1) RETURN
   34:       IF (INCX.EQ.1) GO TO 20
   35: *
   36: *        code for increment not equal to 1
   37: *
   38:       IX = 1
   39:       DMAX = DABS(DX(1))
   40:       IX = IX + INCX
   41:       DO 10 I = 2,N
   42:           IF (DABS(DX(IX)).LE.DMAX) GO TO 5
   43:           IDAMAX = I
   44:           DMAX = DABS(DX(IX))
   45:     5     IX = IX + INCX
   46:    10 CONTINUE
   47:       RETURN
   48: *
   49: *        code for increment equal to 1
   50: *
   51:    20 DMAX = DABS(DX(1))
   52:       DO 30 I = 2,N
   53:           IF (DABS(DX(I)).LE.DMAX) GO TO 30
   54:           IDAMAX = I
   55:           DMAX = DABS(DX(I))
   56:    30 CONTINUE
   57:       RETURN
   58:       END