			PLOTF
			=====


	An interface between application programs and PLOT
	to allow simplified programming.




		Author P.A.Irvine
		C.S.I.R.O. Division of Textile Physics
		338 Blaxland Rd. Ryde.
		N.S.W.  AUSTRALIA  2112


		Date   March 1980

	PLOTF is a series of subroutines which enhance the ease of use
of PLOT (Decus 11-381 by R.N.Caffin and J.Howlett 1979)

	The subroutines in PLOTF allow the following---

1)	Specification of the maximum and minimum values of X and Y 
  for the plot area. When used subsequently the values of X and Y
  are transformed into values suitable for PLOT.

2)	The plotting of points,characters,ASCII strings etc. as
  provided by PLOT,at position (X,Y)

3)	Draw axes with specified start and finish points,and with
  major and minor tics at specified intervals. The coordinate value
  for major tics will be placed on the plot. Separate subroutines are
  provided for plotting both X and Y axes.

		SCALE
		=====

	SCALE is used to set the maximum and minimum values of X and Y
  that the full plot will represent. It is also possible to specify
  perpendicular axes to allow graphs with the Y axis longer than the
  X axis so as to take advantage of the full plotter area.

Calling sequence---

	CALL SCALE ( XMIN,XMAX,YMIN,YMAX,N )

	Where XMIN,XMAX,YMIN,YMAX are the maximum and minimum values
  for X and Y of the plot area.
	N=0 for normal axes,1 for perpendicular.

NOTE--SCALE MUST be called before any calls to XAXIS,YAXIS or PLOTF

		PLOTF
		=====

	PLOTF passes calls of type 3,4,5 and 7 to PLOT with the 
  X and Y values transformed to plot in the area designated by the 
  call to SCALE

Calling sequence---

	CALL PLOTF(X,Y,N,ISC,ICNT,CHAR)

	X,Y are the coordinates
  When	N=3	Jump to point (X,Y) with pen up.
	N=4	Plot point at (X,Y)
	N=5	Draw line from previous position to (X,Y)
	N=7	Plot character string or character given in CHAR
	ISC is the character size. 8 is smallest,32 a good size generally
		If ISC is negative the character(s) are plotted vertically
		ie. up the Y axis.
	ICNT is the number of characters to plot from string,
		if negative continue until null found.
	CHAR is the string,quoted string variable,integer constant
		or integer variable specifying the character(s) to be
		plotted


	A more complete discussion of these calls may be obtained from
	the full description of PLOT.

			XAXIS
			=====

	XAXIS is used to draw the X axis on the plot.
	Major and minor tics may be placed on the axis.

Calling sequence---

	CALL XAXIS (X,Y,XEND,XI,XM,RM,N)

	X,Y	are start coordinates for axis
	XEND	is end point for axis
	XI	is minor tic interval
	XM	is major tic interval
	RM	is length of major tics from axis in terms of Y
		Minor tics are 0.4 times this
	N=0	for tics outside axis
	N=1	for symmetrical tics

	If XM=XI then only major tics plotted
	If XM=0. then no major tics plotted
	If XI=0. then no tics plotted

	If major tics are plotted the value of the ordinate at that
	point will be written on the plot. the character size used
	is 32.


			YAXIS
			=====

	YAXIS is used to draw the Y axis on the plot.
	Major and minor tics may be placed on the axis.

Calling sequence---

	CALL YAXIS (X,Y,YEND,YI,YM,RM,N)

	X,Y	are start coordinates for axis
	YEND	is end point for axis
	YI	is minor tic interval
	YM	is major tic interval
	RM	is length of major tics from axis in terms of Y
		Minor tics are 0.4 times this
	N=0	for tics outside axis
	N=1	for symmetrical tics

	If XM=XI then only major tics plotted
	If XM=0. then no major tics plotted
	If XI=0. then no tics plotted

	If major tics are plotted the value of the ordinate at that
	point will be written on the plot. the character size used
	is 32.

	PLOTF is written in FORTRAN

The subroutines in PLOTF and PLOT may be incorporated in a library
file called PLOTLB.OBJ
This should then be included in the linker command string. eg.
LINK MYPLOT,PLOTLB

All commands to PLOT may be used without restriction except 
2 (SCALE) and 8 (LIMITS).

PLOTF scales X and Y for an origin of (0,0) and maximum 4095 when
it sends the coordinates to PLOT.
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