PRO pixcoord_2d_arr, xsize, ysize, xarr, yarr

; Description: This module creates two-dimensional coordinate arrays representing the pixel coordinates
;              of a two-dimensional pixel array of size "xsize" by "ysize" pixels. The first coordinate
;              array "xarr" represents the x pixel coordinates of the pixel array, and the second
;              coordinate array "yarr" represents the y pixel coordinates of the pixel array.
;
; Input Parameters:
;
;   xsize - INTEGER/LONG - The size of the two-dimensional pixel array in the x direction (pix). If this
;                          value is zero or negative, then it will be reset to the default value of "1".
;   ysize - INTEGER/LONG - The size of the two-dimensional pixel array in the y direction (pix). If this
;                          value is zero or negative, then it will be reset to the default value of "1".
;
; Output Parameters:
;
;   xarr - DOUBLE ARRAY - A two-dimensional array of size "xsize" by "ysize" with values representing
;                         the x pixel coordinates of the two-dimensional pixel array.
;   yarr - DOUBLE ARRAY - A two-dimensional array of size "xsize" by "ysize" with values representing
;                         the y pixel coordinates of the two-dimensional pixel array.
;
; Author: Dan Bramich (dan.bramich@hotmail.co.uk)
;
; History:
;
;   24/07/2008 - Module created (dmb)

;Check that "xsize" and "ysize" are numbers of the correct type, and reset their values if they are out
;of range

;Generate the coordinate arrays for the two-dimensional pixel array