ismax, idmax 

Index of the real vector element with maximum value

FORMAT

  I{S,D}MAX (n, x, incx)

Function Value

  imax                integer*4

                      The index of the first element of the real vector x
                      such that X(1+(imax-1)*|incx|) is the largest of all
                      elements of the vector.
                      If n<=0, imax returns the value 0.

Arguments

  n                   integer*4
                      On entry, the number of elements in the vector x.
                      On exit, n is unchanged.

  x                   real*4 | real*8
                      On entry, a one-dimensional array X of length at least
                      (1+(n-1)*|incx|), containing the elements of the real
                      vector x.
                      On exit, x is unchanged.

  incx                integer*4
                      On entry, the increment for the array X.
                      If incx > 0, vector x is stored forward in the array,
                      so that x(i) is stored in location X(1+(i-1)*incx).
                      If incx < 0, vector x is stored backward in the array,
                      so that x(i) is stored in location X(1+(n-i)*|incx|).
                      If incx = 0, only the first element is accessed.
                      On exit, incx is unchanged.

Description

  ISMAX and IDMAX determine the first  integer i of vector x such that: x(i)
  = MAX{x(j), j = 1,2, ...,n}
  If incx = 0, the computation is a time-consuming way of setting imax = 1.

Example

  INTEGER*4 N, INCX, IMAX
  REAL*4 X(40)
  INCX = 2
  N = 20
  IMAX = ISMAX(N,X,INCX)

  This FORTRAN example shows how to compute the index of the vector element
  with maximum value.