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<HTML>

<HEAD>
<TITLE>Xmgr: plot functions</TITLE>
</HEAD>

<BODY>
        <h2> <a NAME="graph">Plot functions</a> </h2>
<p>
The selections in the Plot pulldown menu allow the modification of 
plot parameters. There are popups for setting the scaling of the axes, the 
number of tick marks to display, legends, writing annotative text, and 
drawing objects such as lines and boxes. 
<p>
xmgr uses 3 coordinate systems 
in drawing a graph. These are the world, viewport, and device coordinate 
systems (following Foley and Van Dam). The world coordinates system is the 
one in which the data are defined and constitutes the user's coordinate 
system. The viewport coordinate system (in xmgr), is a rectangle defined 
by the points (0.0, 0.0) or the lower left corner of the device and 
(1.0, 1.0) or the upper right corner of the device. The pipeline for 
drawing objects on the screen or hardcopy device is a pair of linear 
transformations that carry points in world coordinates to the viewport 
and then on to the device coordinate system. The upshot is that an 
object located in world coordinates can be drawn in various parts of 
the screen or hardcopy device depending on the scaling while an object 
located in viewport coordinates remains in the same spot regardless of the 
world scaling. Strings, lines, boxes, and the graph legend can be located in
either world or viewport coordinates.
<p>
<HR>

        <ul>
	  <li><a href="#world">World scaling</a>
	  <li><a href="#view">Viewport</a>
	  <li><a href="#autoscale">Autoscale</a>
	  <li><a href="#title">Titles</a>
	  <li><a href="#ticks">Ticks labels/tick marks</a>
	  <li><a href="#frame">Frame</a>
	  <li><a href="#symbols">Symbols</a>
	  <li><a href="#errorbars">Error bars</a>
	  <li><a href="#legends">Legends</a>
	  <li><a href="#strings">Strings & Things</a>
	  <li><a href="#timestamp">Time stamp</a>
        </ul>
<p>
<HR>
	<h3> <a NAME="world">World scaling</a> </h3>
<p>
Define the world coordinate system by filling in the items Xmin, Xmax, Ymin, 
and Ymax. The plot is drawn in world coordinates in a rectangle described by 
the two points (Xmin, Ymin), (Xmax, Ymax). The input is scanned for arithmetic 
expressions so setting Xmin = -PI and Xmax = PI is legal input (see the 
section on transformations for a description of the syntax and available 
functions). The tick spacing can also be set in this popup by filling in 
the items for the major and minor spacing for each axis. `Update world/ticks' 
is used, when, occasionally, the state of the items used to define the world 
scaling get out of sync with what is actually used to draw the graph, 
clicking on this item synchronizes the internal values with the displayed 
values. Press the button marked <b>Accept</b> to inform xmgr of the changes.
<p>
Note: make sure Xmin &lt Xmax and Ymin &lt Ymax.
<p>
<HR>
	<h3> <a NAME="view">Viewport</a> </h3>
<p>
Define the viewport by filling in the items Xmin, Xmax, Ymin, Ymax. 
Viewport coordinates run from (0.0,0.0), the lower left corner of the 
screen or hardcopy device, to (1.0,1.0), the upper right corner of the 
screen or hardcopy device. Press the button marked <b>Accept</b> to make 
the change to the new viewport. Press the <b>Pick view</b> button to use 
the mouse to define the viewport. Take the mouse to the lower left corner 
of the desired viewport and press the left button (there is no need to 
hold the button down). A rubberband box will show you the current size of 
the viewport you may select. When you are satisfied with the view, press 
the left mouse button again to activate the new viewport.
<p>
Press the button marked <b>Close</b> to close the <b>Viewport</b> popup.
<p>
The viewport can also be changed by double clicking on the focus markers (or
where they would be placed if not shown). The new location is chosen by clicking
the first mouse button.
<HR>
	<h3> <a NAME="autoscale">Autoscale</a> </h3>
<p>
Use the Autoscale popup to set parameters associated with autoscaling. 
Select the axis to scale, or none. Selecting none allows the autoscale 
type and the number of ticks to create to be set but no autoscaling is done. 
Select the particular set to use or All. The Autoscale type sets the method 
of autoscaling, either Auto or fixed. Auto uses a method based on 
routines posted to the net by Paul Heckbert and generates nice looking 
tick spacing, but alters the scaling of the axes. The fixed option uses 
the minimum and maximum values in the set (or over all sets) to set 
the scale of the axes. Select the number of tick marks to use for 
defining the tickmark spacing (in the case of Heckbert scaling, these 
settings are advisory only). The item labeled <b>Apply to:</b> allows the 
autoscaling of the current graph, or all active graphs. 
<p>
<HR>

	<h3> <a NAME="title">Title/subtitle</a> </h3>
<p>
The title and subtitle are strings that appear centered at the top of the plot. 
Fill in the items indicated and press the button marked <b>Accept</b>. To 
change the font, color, or character size used for titles use the items 
from the popup denoted <b>Props...</b>.
<p>
<HR>
	<h3> <a NAME="ticks">Ticks/tick labels</a> </h3>
<p>
Set the spacing and type of major and minor tick marks, definition of axes 
labels, and toggle features associated with the drawing of the graph axes. 
<p>
The top item, <b>Edit</b>, selects the axis for which the feature selections 
will apply. There are two axes defined for each co-ordinate direction, the 
primary axis and the zero axis. The primary axis will be used the most, the 
zero axis is, by default, turned off. The button to the right of the 
<b>Edit</b> item labeled <b>Props...</b> allows the axis to be offset 
by a specified amount in viewport co-ordinates. The item <b>Axis label</b> 
accepts the definition of the label to be used when drawing the axis. 
Various properties of the label may be set in the popup just below 
labeled <b>Axis label props...</b>.
<p>
The two items `Major tick spacing' and `Minor tick spacing' set the spacing 
of major and minor ticks. Tick labels are drawn based on the setting for 
the major tick spacing. These items are duplicated in the `Define world' 
popup described previously. Fill in the appropriate blanks and press 
<b>Accept</b> to refresh the display. The units are positive deltas 
starting with the world minimums. Input is run through the scanner 
so expressions are allowed. The are special symbols <b>dx</b> and <b>dy</b> 
for setting a prescribed number of tick marks. Dx is the distance along the 
X-axis and dy is the distance along the Y-axis, as defined in the current 
window of the world coordinate system. Typing at <b>Major tick spacing</b> 
"dx/10" will give 10 major tickmarks.
<p>
Tick labels, tick marks, the axis bar, may be toggled by the check boxes. 
Properties for each of these can be set by the <b>Props...</b> popups 
associated with each item.
<p>
Properties for tick labels are:
<dl>
	 <dt>Font
		<dd>Which font to use when drawing the labels.
	 <dt>Color
		<dd>Which color to use.
	 <dt>Line width
		<dd>Width of line to use when drawing the label.
	 <dt>Char size
		<dd>Size of characters to use.
	 <dt>Format
		<dd>Decimal, exponential, power, general plus 
several time and date formats. 
To use the time and date formats, the data are required to be in Julian 
Date format, the long version. Two auxiliary programs, jul2greg and 
greg2jul, are available with the distribution to assist in the conversion 
from Julian to Gregorian date formats.
	<dt>Stagger
		<dd>each tick label may be offset with respect to its 
neighbor, the levels of staggering ranging from 0 to 3, This is especially 
useful with some of the time and date formats.
	<dt>Precision
		<dd>sets the number of places to display to the right 
of the decimal point for the labels.
	 <dt>Skip every
		<dd>tick labels are drawn at every major tick mark, use 
the skip factor to circumvent this.
	 <dt>Start labels at
		<dd>Graph minimum, or specified. To start the labels 
at some other point than the graph minimum, fill in the text item to 
the immediate right with the value where tick labels are to begin. There 
is a similar item in the property sheet for tick marks that can be used 
to set where the major tick marks begin. between these two, 
there should be sufficient flexibility.
	 <dt>Stop labels at
		<dd>same as above only works at the other end of the axis.
	 <dt>Layout
		<dd>allows the tick labels to be drawn horizontally, 
vertically, or a specified angle (in degrees).
	 <dt>Draw tick labels
		<dd>which side of the graph to draw tick labels, either 
the normal side (the bottom of the graph in the case of the X-axis, or to 
the left of the graph in the case of the Y-axis), The opposite side, or 
both. This can be handy when using multiple axes, or overlaying graphs 
with differing scales.
	 <dt>Sign
		<dd>allows the numerical value of the label to be displayed 
as is, as its absolute value, or negated. This can be used to effectively 
reverse the sense of the axis (negate), or reflect the axis about zero 
(absolute value).
	 <dt>Apply to
		<dd>Override the selected axis from the Ticks/tick 
label popup, causing the settings to be selected for all axes in the 
current graph, the current axis for all graphs, or all axes in all graphs.
</dl>
<p>
Press the button <b>Accept</b> when everything is OK, or <b>Close</b> to 
close the popup.
<p>
Properties for tick marks are:
<dl>
	 <dt>Tick mark direction
		<dd>in, out, or both. Which direction the ticks point.
	 <dt>Tick marks on
		<dd>Which side of the graph to draw ticks. The normal 
side is the bottom of the graph in the case of the X-axis, or to the 
left of the graph in the case of the Y-axis, the default is to draw 
ticks on both sides.
	 <dt>Major tick length
		<dd>sets the length of major tick marks
	 <dt>Minor tick length
		<dd>sets the length of minor tick marks
	 <dt>Major grid lines
		<dd>a check box that when toggled on, grid lines will 
be drawn at the settings for major tick marks.
	 <dt>Minor grid lines
		<dd>a check box that when toggled on, grid lines will be 
drawn at the settings for minor tick marks.
	 <dt>Color, line width, and line style
		<dd>These items set the characteristics of the lines use 
to draw ticks and grid lines.
	 <dt>Apply to
		<dd>allows the axis select in the Ticks/tick label popup 
to be overridden, causing the settings to be selected for all axes in the 
current graph, the current axis for all graphs, or all axes in all graphs.
<p>
Press the button <b>Accept</b> when everything is OK, or <b>Cancel</b> to 
close the popup.
<p>
Properties for the axis bar are:
<p>
	 Color, line width, and line style items set the characteristics of the lines use to draw 
ticks and grid lines.
</dl>
<p>
Press the button `Accept' when everything is OK, or `Cancel' to close the popup.
<p>
<b>IMPORTANT NOTE FOR LOG PLOTS:</b>
When log scaling is selected for a particular axis or axes, the meaning of 
major and minor ticks changes slightly. Major ticks should be set to integer 
values. Use minor ticks to set the number of interdecade tickmarks, these 
should be set to integer values ranging from 0 (no interdecade tickmarks) to 5. 
A value of 1 will draw each interdecade position, 2 will skip every other 
position, etc.
<p>
<HR>
	<h3> <a NAME="frame">Frame</a> </h3>
<p>
The frame is the box drawn around the clipping region of the graph, and the region inside. Items in the frame popup are:
<dl>
	 <dt>Frame
		<dd>Turn the frame on or off.
	 <dt>Style
		<dd>Either `closed' or `open.
	 <dt>Color
		<dd>Set the color of the line drawn around the graph.
	 <dt>Line width
		<dd>Set the width of the line around the graph.
	 <dt>Line style
		<dd>Set the line style of the line.
	 <dt>Fill graph background
		<dd>Toggle the filling of the frame. 
	 <dt>Background color
		<dd>The color with which to fill the frame.
</dl>
Press <b>Accept</b> to register the settings, <b>Close</b> to close the popup.
<p>
<HR>
	<h3> <a NAME="symbols">Symbols</a> </h3>
<p>
The items in the symbols popup allow the selection of symbols, lines, 
and fill style to be used when drawing a set.
<p>
Items in the symbols popup are:
<dl>
	 <dt>Select set
	   <dd>The set or sets to which the following items will apply.
	   Multiple selections may be activated.
<p>
<b>Symbol:</b>
<p>
<dt>Symbol
<dd>Select the symbol to use, or none for no symbol.
<dt>Fill
<dd>Select the fill option, none, filled, or opaque. The opaque option 
allows the symbol to be filled with the background color (white as of 
this writing) overwriting the line used to connect each point.
<dt> Size
<dd>Set the size of the symbol.
<dt> Char
<dd>select a character to use instead of a symbol (not active)
<dt> Skip
<dd>select the number of points to skip when drawing symbols
<p>
 <b>Line:</b>
<p>
<dt> Style
<dd>select the line style for the lines connecting the 
points in the set.
<dt> Width
<dd>select the line width for the lines.
<dt> Color
<dd>the color to use when drawing lines.
<p>
<b>Fill:</b>
<p>
<dt> Fill
<dd>select the type of fill, none, as polygon, to y=0.0, x=0.0, 
x=graph Xmin, x=graph Xmax, y=graph Ymin, y=graph Ymax.
<dt> Fill using
<dd>either Color or Pattern.
<dt> Color
<dd>select the color to use, or none.
<dt> Pattern
<dd>select the pattern to use or none
There are three additional buttons in this popup that can be used to 
set the colors, symbols, and line widths in an incremental fashion, 
avoiding the need to specify a each.
<p>
<b>Misc:</b>
<p>
<dt> Legend
<dd>A string defining the legend to use for this set
<dt> Select
<dd>Allow single or multiple choices in <b>Select set</b>
<dt> All colors
<dd> Assign a different color to each set
<dt> All symbols
<dd> Assign different symbols to each set
<dt> All widths
<dd> Cyclically Assign different line widths to each set
<dt> All line styles
<dd> Cyclically assign different line styles to each set
<dt> B/W
<dd> Make all line colors black
<p>
<b>Misc:</b>
<p>
<dt> Legend
<dd>A string defining the legend to use for this set
<dt> Select
<dd>Allow single or multiple choices in <b>Select set</b>
<dt> All colors
<dd> Assign a different color to each set
<dt> All symbols
<dd> Assign different symbols to each set
<dt> All widths
<dd> Cyclically Assign different line widths to each set
<dt> All line styles
<dd> Cyclically assign different line styles to each set
<dt> B/W
<dd> Make all line colors black
<p>
<b>NOTE: There are limits on how large a set can be for the fill to
operate correctly. The limit for the display is approximately 8000 points,
for the hardcopy drivers, this limit drops to around 800-1000.</b>
</dl>
<p>
 Symbols descriptions:
<ul>
	<li> 1.	No symbol
	<li> 2.	Dot
	<li> 3.	Circle
	<li> 4.	Square
	<li> 5.	Diamond
	<li> 6.	Triangle up
	<li> 7.	Triangle left
	<li> 8.	Triangle down
	<li> 9.	Triangle right
	<li> 10. Plus
	<li> 11. X
	<li> 12. Star
	<li> 13. Impulse at X
	<li> 14. Impulse at Y
	<li> 15. Vertical line at X
	<li> 16. Horizontal line at Y
	<li> 17. Histogram X
	<li> 18. Histogram Y
	<li> 19. Stair step X
	<li> 20. Stair step Y
	<li> 21. Bar X
	<li> 22. Bar Y
	<li> 23. Range
	<li> 24. Location
	<li> 25. Set #
	<li> 26. Set #, location
	<li> 27. Bar and whisker (not active as of this writing)
	<li> 28. Segments
	<li> 29. Character
	<li> 30. String (not active as of this writing)
	<li> 31. Hi low X
	<li> 32. Hi low Y
	<li> 33. Open/close X
	<li> 34. Open/close Y
</ul>
<p>
 NOTE: symbols 16-29 do not appear in the legends
<p>
<HR>
	<h3> <a NAME="errorbars">Error bars</a> </h3>
<p>
Error bars are created by reading in the data as a set with error bars (see Files above). 
Properties of error bars are set by opening the `Error bar props' popup.
<dl>
<dt>Size
<dd>Set the length of the error bar.
<dt> Line width
<dd>Set the line width of the error bar.
<dt> Line style
<dd>Set the line style of the error bar.
<dt> Riser
<dd>Toggle the display of the line connecting the error bar with the data point.
<dt> Riser line width
<dd>Set the width of the riser.
<dt> Riser line style
<dd>Set the riser line style.
<dt> Display
<dd>Toggle the display of the error bar.
</dl>
<p>
<HR>
	<h3> <a NAME="legends">Legends</a> </h3>
<p>
Legend items:
<p>
<dl>
<dt>Legend on/off
<dd>toggle the display of the graph legend
<dt>Legend location type
<dd>Select the coordinate system to use when interpreting the legend x, and legend y items described below. Either the world or viewport coordinates. 
Legends placed in viewport coordinates make the legends stay put as the plot scale 
changes. Legends placed in world co-ordinates will float as the graph scaling is 
changed.
<dt> Legend gap
<dd>specify the vertical gap between legend entries
<dt> Legend length
<dd>specify how long the line representing the set should be.
<dt> Legend X
<dd>X value of legend location
<dt> Legend Y
<dd>Y value of legend location
<dt> Font
<dd>specify the font for the legend labels
<dt> Frame
<dd>toggle a box drawn around the legend. The three items below set the 
line color, line width, and line style of the box.
<dt> Fill frame
<dd>toggle the fill of the box around the legend. The frame fill will 
obliterate anything beneath, grid lines, sets, etc. Set the type of fill 
either color or pattern and the corresponding color or pattern.
</dl>
<p>
Clicking <b>Place</b> is a convenient method of placing the legend 
on the canvas. After pressing this button, move the mouse pointer to the 
desired location and press again with the left button. The location will 
be in world or viewport coordinates as selected above.
<p>
<dl>
<dt>
Press <b>Edit...</b> to edit legend labels.
<dd>
<ul>
<li>To edit a label, click on the desired set or use arrow
keys and enter the label in the
<b>Label</b> area. 
Press return to enter the change in the set list and then press 
<b>Accept</b> to apply it to the graph.
<li> <b>Load comments</b> will make the set comments the legend labels.
<li><b>Strip labels</b> will remove the leading component of a pathname and 
leave only 
the basename.
</ul>
</dl>
Press the button marked <b>Accept</b> to register the legend settings.
<p>
Press the button marked <b>Close</b> to close the popup.
<p>
<HR>
	<h3> <a NAME="strings">Strings & Things</a> </h3>
<p>
The numbers of strings, lines, boxes and ellipses are fixed, open Help/About 
to see what
the limits are for your version of xmgr. 
<dl>
<dt> To define a text string to be drawn on
the canvas:
<p>
<dd>
Select font, pen, justification, rotation (in integer degrees [0,360]),  size.
Press the button marked "Text" to activate the text writing routines.  Move the
mouse to the canvas and press the left mouse button at the desired  location
and type away. 
It is possible to use 
<a href="fonts.html">control codes </a>
to change fonts within the string.
Press &ltreturn&gt to advance to the next line - the right 
mouse button to stop. 
Each line of text is a separate object.
The text cursor does not behave properly for rotated 
strings. To redefine string parameters you'll need to press the right button 
to leave text mode - adjust the parameters and press "Text" again to inform 
xmgr of the changes and resume writing. 
See below for an explanation  of world/viewport positioning.
<p>
To click on a text string, the cursor must be placed near the origin of
the text string. 
The origin will be the lower left corner of the string for left justified
strings, the right side for right justified strings and in the center for center 
justification. 
<p>
NOTE: It is necessary to press &ltreturn&gt to register the string.
<p>
<dt> Edit string
<dd>
Click on the string you want to edit. A cursor will appear at the end of the
string which may be moved using the left and right arrow keys. 
Anything typed will be inserted at the cursor and backspacing will delete the
character before the cursor. In addition, the following control characters 
have special meanings:
<p>
<dd>
^a - Move editing cursor to beginning of string
<p>
^e - Move editing cursor to end of string
<p>
^u - Delete beginning of string to cursor
<p>
^k - Delete to end of string
<p>
<dt> To define a line, box or ellipse to be drawn on the canvas:
<p>
<dd>
Set the properties of the object you want to draw by selecting
box/line/ellipse props...
<p>
The cycle "Position in: World | viewport coordinates" allows the object 
position to be defined in the world coordinate system or viewport 
coordinates. In World coordinates, the object 
position and aspect ratio 
on the display change as the plot is re-scaled. Specifying the 
object in viewport coordinates will force the object to 
remain in the same place and retain the same aspect ratio
as the plot scale is changed.
<p>
When the cursor turns to cross-hairs, the two points defining the object may
be specified. A line is defined by its end points while a box is defined by
its opposing corners.
An ellipse is defined by the opposing corners of the rectangle enclosing it.
<p>
<dt>Selecting an object
<p>
<dd>
	For the following three operations, one must select an object.
	This is performed by clicking the left mouse button near one of the
	defining points of an object. Only objects associated with the current 
	graph will be selected. Objects are associated with the graph that was
	active at the time of their creation.
	The defining points of objects are given below<p>
	<dl compact>
	<dt> box <dd> corners
	<dt> ellipses <dd> corners of bounding box
	<dt> line	<dd> end points
	<dt> text <dd> origin (justification dependent)
	</dl>
	<p>
<dt> Move object:
<p>
<dd>
	To move a line, box, ellipse or string:
<p>
	Press the button marked "Move", this should change the cursor to 
the "move" cursor.
<p>
	Select the object to be moved. The object will now be drawn with
	the first point used to define the object under the cursor.
<p>
	Move the cursor to the new location and press the left mouse button.
<p>
<dt> Delete object:
<p>
<dd>
	Press the button marked "Delete", this should change the cursor 
to a bullseye cursor.
<p>
	Select the object to be deleted.
<p>
<dt> Edit object:
<p>
<dd>
	Click on edit and then select an object.
	<p>
	The attributes of an object may be changed after it has been defined
	by clicking on the object.
	Editing may be used to redefine a line, box, ellipse or string.
	<p>
	The <b>World&lt-&gtView</b> button is used to interchange between 
	world and viewport specification of object placement.
	The object will remain at the same spot when converted from one 
	coordinate system to the other.
<p>
<dt>
NOTE:
The right mouse button cancels all operations (true throughout xmgr 
with respect to mouse operations).
</dl>
<HR>
	<h3> <a NAME="timestamp">Time stamp</a> </h3>
<p>
Set the display of a string containing the current time. This string is updated
each time the graph is redrawn.
<p>
<HR>

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