contours

	contours(nx.i4.v, ny.i4.v, xx.r4a.r, yy.r4a.r, data.r4a.r,
		 number_contours.i4.v, contour_value.r4a.r,
		 contour_color.i4a.r)

	This routine creates a contour plot.  The plot axes must have been
	set up and the window set active by the caller.

	nx		number of grid points in the X direction
	ny		number of grid points in the Y direction
	xx		array containing the X coordinates of the grid lines
	yy		array containing the Y coordinates of the grid lines
	data		array containg the data stored as data[ny][nx]
	number_contours	number of contour lines to be displayed
	contour_value	array containing the contour values
	contour_color	array containing the color of each contour line

	This function requires the following include files:

	ul_cbsaux_h:contours_h.h_h

	Related functions:

	wn_view(_c), wn_world(_c), wn_axis_label(_c), wn_active(_c),
	intro_graphics_windows

	C/C++ usage:

	#define	NX		(number of grid points in x direction)
	#define	NY		(number of grid points in y direction)
	#define	NCONTOURS	(number of contour lines desired)

	int	nx = NX;
	int	ny = NY;
	int	number_contour = NCONTOURS;
	int	contour_color[NCONTOURS];
	int	window_id;
	float	xx[NX];
	float	yy[NY];
	float	data[NY][NX];
	float	contour_value[NCONTOURS];

    Fill in xx,yy,data,contour_value,contour_color arrays 

    Use wn_ routines (CLIB GRAPHICS WINDOWS) to define axis and viewport

 	wn_view_c(&window_id......);
	wn_world_c(window_id,......);
	wn_active_c(window_id);
	wn_axis_label_c(WN_HORZ,.....);
	wn_axis_label_c(WN_VERT,.....);

	contours(nx,ny,xx,yy,data,number_contour,contour_value,contour_color);