isMonotonic

Check a one dimensional array to see if it is monotonic.

Prototype

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"  ; This library is automatically loaded
                                                             ; from NCL V6.2.0 onward.
                                                             ; No need for user to explicitly load.

	function isMonotonic (
		x [*] : numeric   
	)

Arguments

A one-dimensional numeric array.

Return value

Returns

        0 if the array is not monotonic.
        1 if the array is monotonically increasing.
       -1 if the array is monotonically decreasing.

Description

Applies a simple test for monotonicity. An array is monotonically increasing if each value increases and monotonically decreasing if each value decreases.

Examples

Example 1

      load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"

      x = ispan(1,10,1)
      y = -x
      z = (/-5.2,-4.3,-2.2, 0, 1.7, -4.1, 9.9/)

      i = isMonotonic(x)     ; i= 1
      i = isMonotonic(y)     ; i=-1
      i = isMonotonic(z)     ; i= 0