The commands are given their full English names here (though only four characters are needed). The characters following the first blank after the command word itself are termed the `command field'. A command line may be 120 characters long. Parameters that may be omitted in the command field are enclosed in brackets; alternates are indicated by slashes. The parameters may be numbers, file names or text; it should be obvious from the context which is appropriate. A list separated by slashes denotes a set of possible alternative items. A line beginning with one or more spaces is ignored and may be used as a comment. In mathematical formulas an asterisk denotes multiplication and double asterisk exponentiation.
With 4 numbers: transforms the x and y coordinates of the next and
subsequent data series to be read according to new(x) = a*x + b,
new(y) = c*y + d. With 6 numbers: uses new(x) = a*x + b*y +
c, new(y) = d*x + e*y + f. This is an affine transformation.
Blank command field: cancels current transformation
Paint the rectangular region framed by the current axes uniformly with the specified color; see command color for how to specify the color, and palette on how to customize it. The background is opaque, so that it will cover previous plots if the current graph lies on top of earlier material; this makes the color white useful. Setting color to - (minus) returns to the transparent background.
When note is included the background color is applied instead
to a rectangular region around each of the notes. Often the color
is white (or that of the graph background) and then the text will
appear to be posted on top of the graphical material and grid lines.
This option does not work for notes in an external file.
Blank command field: retain previous setting
Removes the last n data series read into memory. If no series have
been read in, do nothing. If n is greater than the number of series
currently present, all the series are removed without complaint.
Blank command field: n = 1
Change the height of the lettering in titles, labels, notes and axis
numbering to h inches. The new value applies to the subsequent text
to be read, so that different height letters can appear in the title,
the axis notations, etc. The value of h just before plot
determines the height of the axis numerals. The optional parameter
angle specifies the angle (counterclockwise) at which text will be
plotted in the next note. Letter height can also be controlled
by the a special text phrase (see LETTERING).
Default: h = 0.08, angle = 0
clear [notes] [text] [axes] [read] [data]
Plotxy carries forward almost all attributes from a previous
graph to the next, but it is often useful to keep some but not others.
With notes this command erases the notes, or with text
all labels, titles and notes. The axes option returns the
axes to linear in x and y, places them at the bottom and left with
default lengths and undefined ranges. The option read resets
the read attributes to mode 2, straight-lines interpolation,
no affine transformation, and input from the terminal (file *).
Data deletes all the data series. All of these actions can
be achieved with other commands (see cancel, notes,
xlim, etc), but clear offers a concise alternative for
a common requirement.
Blank command field: clear everything
color color
color [pale/light/dark] color
color n
This command sets a new color from the list: black, red, blue, green,
brown, orange, yellow, purple (aka magenta), gray, cyan, white.
White is useful for drawing on top of dark curves. The shade can
be modified with the second form; light colors are best with the
fill or background commands. Pale colors are even lighter.
See palette for a way to customize the colors; then the new
colors are associated with numbers, n. The color assigned to a data
series is the one in force at the time of the associated read
command; similarly with axis labels, notes, etc. The axes and frame
are drawn in the color specified at the time plot is called.
Default black
The next data series to be read will be drawn as a dashed line, with
visible segments s1 inches long and missing segments s2 inches long.
If s3 and s4 are included the pattern now repeats with four elements,
s1 and s3 representing the lengths of the visible segments, and s2 and
s4 describing the gaps. Sensible choices are made if the user enters
only one or three values rather than an even number. dash is
an input attribute applying to the next read command. To return
to an unbroken curve, set s1 or s2 to zero.
Default: s1 = 0, s2 = 0
Blank command field: s1 = 0.03, s2 = 0.05
feet h
When error bars are drawn they are provided with feet, which are
short, perpendicular segments terminating the bar. By default their
size is that of the current letter height (see char). This
command supersedes that default with the height h inches, probably
most usefully with h=0.
Default: h=letter height
Blank command field: return to default setting
Defines the file name of the diskfile from which data are to be read;
or the symbol * which implies read from the terminal. The name
must consist of 64 or fewer characters. After this command the
next read statement will begin at the beginning of the file.
See NOTE 11 for the special file O which contains points on
a unit circle.
Default: *
Blank command field: Rewind current file
Fills a closed polygon based on the next input series with the current color. A closed curve is created by joining the first and last points of the series with a straight line. Fill, unlike most commands, does not remain in force, but applies only to the next read. Solid symbols are invoked with the symbol command. If parts of the curve go outside the plot window, the results are unpredictable. Also a polygon with a dashed boundary will not be filled. Plotxy plots the data series in the order they are input; this allows the user to cover up parts of the graph with filled regions. Notes are plotted last on top of any filled areas. See also background.
An obsolete command from the days when Fortran was king: defines a Fortran format for reading the next data series. The format specifier may be
(1) a normal Fortran format specifier enclosed in parentheses, for example: (2g12.4)
(2) the single character * meaning `format free' reading
(3) the single character b meaning a Fortran binary read.
In each case the data are read with a single Fortran read statement of
the appropriate type. In type (1) never use an I format because values
are stored as REAL variables; thus a number written with I4 must be
read with an F4.0 format. Always remember the space after the word
format and the parentheses in mode (1). If the numbers can be
unambiguously read by a person there is no need to invoke this command.
Default: *
Blank command field: *
frame +box -box grid -grid none
frame -xnum -ynum -xaxis -yaxis
frame top/bottom left/right
frame +xeven +yeven
If +box is present, two more sides are added to the axes to complete a rectangular box around the plot; -box removes the box. grid adds a light grid corresponding to the axis tick marks as well as adding a box; grid-dash draws dashed grid lines rather than solid ones; -box cancels the grid and the surrounding box and returns to the normal situation with two orthogonal axes. -grid removes the grid but not the box. The option none strips the graph of axes, the box and the grid.
The second form of the command allows you to delete the numerical annotation from either axis: with -xnum the numbers are removed from the x-axis; with -ynum from the y-axis. The tick marks remain; they may be removed by setting the character height to zero immediately before plotting. Numbers can be restored with +xnum and +ynum. Similarly a complete axis may be removed with -xaxis or -yaxis, and restored later with plus signs. When contradictory options are issued (-xaxis and +xaxis both present, for example) plotxy takes the option omitting the least amount of information.
The third form allows the user to draw an axis on the "wrong" side of the graph: at the right or at the top; the labels move with the axes. Obviously bottom and left restore the axes to their conventional locations.
The last form controls the tick mark style: normally numbered ticks
are larger than those without numerical labels. The desirability of
this arrangement is not always unambiguous. The height of the ticks
on an axis can be made even with +xeven for the x axis, +yeven for
the y axis. The default is restored with -xeven, -yeven.
Default: -box
Blank command field: +box
Lists the four-letter abbreviation of all the commands. This may remind you of a name you have forgotten. Some systems also allow access to the documentation file.
Causes the output to be rotated by 90 degrees clockwise, that is, landscape mode. The command must be issued before the first plot command in order to be effective. The orientation state cannot be changed back to the conventional (portrait) style unless a new plotfile is created with output. Then, if landscape is used a second time, before the first plot on the new file, the state is reversed from its current one.
logxy [style]
logxy [n]
Specifies the type of scales for the next plot with one of the following styles: linlin, loglin, linlog, loglog, linlogy+, loglogy+, equilin where the first syllable describes the x axis, the second the y axis, so that loglin means the x axis is logarithmic and the y axis linear, and so on. The style may also be specified by an integer: 0 linlin, 1 loglin, 2 linlog, 3 loglog. If nonpositive data values are encountered, plotxy switches to linear axes, unless one uses linlogy+ or loglogy+: either of these causes nonnegative y values to be ignored, and the positive values to be plotted on the log y axis.
Somewhat obscurely, style may also be equilin (or 4). Then a
linear scaling is performed, but instead of scaling x and y separately,
the data are scaled equally and sized to insure the data area is
contained within the plot window. The original proportions of the
data are preserved, circles remain circles, etc. The values of x1,
x2, y1, y2, in xlim and ylim must be unset (or zero).
Default: linlin
Blank command field: loglog
Defines how the input data are grouped in the next and subsequent read commands. The integer n may be 1, -1, 2, 3, -3, 4 or 10, -10, 20, 30, -30: mode 1 implies data are simply consecutive y values with x uniformly increasing, beginning at x = 1 and unit increment (these x values may be modified with affine); mode = -1 means that x values are read and that y increases uniformly from 1 with unit increment; mode = 2, the default, means data are x, y pairs; 3 means data are x, y, z triples in which z is taken to be the uncertainty in y (an error bar is plotted between y-z and y+z). mode = -3 means the third member of data group is the uncertainty in the x-value. A symbol may be plotted at the actual value of y itself if symbol is set. If s, the symbol height, is set greater than or equal to 10, a symbol is drawn with height z instead of the bar. Also see feet. When mode is 4 the x and y data must be read by separate read commands, the x series being input first. The series length is that of the x series.
In modes 10, 20, 30, it is assumed the input file is in the form of a table. For mode 10 the single column, col1, is selected to be plotted against uniform x. With -10 x is plotted against uniform y. Similarly mode 20 allows you to read x from col1 and y from col2 from the table. For example, mode 20 5 2 means column 5 is used for x and column 2 for y in the x-y series. Modes 30 and -30 are similar, picking the three columns from the table in the obvious way. In these modes any supplied format is ignored and replaced by *. The columns are separated from each other by spaces (not commas or tabs), and skipped columns may contain non-numerical material.
Asymmetric error bars can be input in modes 30 and -30 by giving four columns, instead of three. Then col1 and col2 contain x, y for the data point as before, col3 now holds the lower end of the error bar, col4 the upper end.
If fill is issued before a mode 3 read, and no symbol is
indicated, a filled corridor is plotted, and the feet are omitted.
Default: n = 2
Blank field: after n = 10, 20, 30, col1 = 1, col2 = 2, col3 = 3
In normal operation command lines can be annotated by comments, indicated by the % sign. Everything after a % on the line is ignored. But users may wish to use the symbol % in labels, notes, file names and so on. Including this command causes the commenting facility to be permanently turned off from that point on, thus restoring the use of % to the user.
note (x y [in] [c] [r]) text
note (p q x y [in] [c] [r] [f]) text
note (+) text
note (v[c] [r]) text
note filename
In the first two options above, plotxy reads the characters of text to be plotted on the graph at the coordinates x, y (which do not participate in the current affine transformation). The text may be up to 80 characters in length. If the optional in appears, the coordinates (x, y) refer to the bottom left corner of the first text character, measured in inches from the intersection of the axes; otherwise x, y are in the units of the graph. Normally, the coordinates x, y refer to the bottom leftmost point of the first character of the text, but if the letter c appears, the text is centered above the point (x, y); and if r appears, the base of the end of the line is placed there (right justification). Notice the parentheses surrounding the coordinates are mandatory. The height of the plotted characters is the value h in the most recent character command. Similarly the angle the text makes with horizontal is the one previously set in character. To see how many separate notes are allowed in your version of plotxy, enter status (200 is common). To delete the notes, enter note and a completely blank command field, or use clear. Old notes must be cleared for new graphs with fresh set of notes, otherwise notes from the previous plot will be carried forward onto the current one.
If no coordinates are supplied, but a single + appears instead, the text is appended to the material of the previous note, thus overcoming the limitation on character count in a single note.
If a single v appears, place the new material vertically under the previous note, left justified. With vc center the new line under the previous one, and with vr right justify the new text.
Notes may be written on an opaque background covering up other material if desired; see background.
If four coordinates instead of two appear in the parentheses, an arrow is drawn with its tip at p, q and its tail tastefully near the text, which is plotted as before with x, y as specified by r, c, or left justified by default. The text is always horizontal with this option. The letter f following the coordinates causes the arrow head to be filled in. If no text accompanies a four-coordinate note, the arrow tail goes exactly to the second position.
The following option allows a large number of short notes to be read
from a file. When a filename follows the command, coordinates and
notes (one set per line) are read from the named diskfile to its end.
Up to 600 such notes can normally be read (Use status to check
this). Each note in the notefile is at most 16 characters long and the
whole series comprises text, homogeneous in character size,
angle, and color specified at the time when the file is read.
Font changes can be induced in the usual way by phrases in the
notes themselves. The coordinates are in graph units only and
must not be enclosed in parentheses. The notes are all left
justified. These notes are canceled by note with a blank command
field just like those specified as commands. If it is desired to
begin the note with a space, terminate the coordinates with a comma;
spaces after the comma are part of the note.
Blank field: delete all old notes
Defines the name of the plot file to be filename, which must
be composed of 64 or fewer characters. Every time output
is issued, the currently opened plot file is closed and a new one
opened ready to receive further plots. Suppose you make a mistake;
if you enter the command output without a filename the current
plotfile is erased. Subsequent output is sent to the current file
which has been re-initialized.
Default: mypost
Blank command field: restart plot in current file
Assign to the integer n to a color with hue h, saturation s, and
brightness b. Normally n should lie between 45 and 68. For n in the
range 1 to 44, existing colors will be changed. The command may be
repeated with different n to load a selection of colors.
Palette sets the colors for the next graph to be drawn, not the
next data series, so that resetting the color for same integer n
several times will result in only one color being chosen, the last
one set. The three HSB color coordinates (h, s, b) are defined in
any book on PostScript: Roughly, h goes continuously around the
color circle: from 0 (red), to 0.333 (green) to 0.667 (blue) back to
1 (red again); s sets the amount of white mixed in: it ranges from 0
(all white) to 1 (no white - full saturation); b is brightness: from
0 (black) to 1 (maximum brightness).
Blank command field: do nothing
plot [top/center/bottom] [left]
plot [up/down/right/left/top]
plot [x0 y0 [abs] ]
Creates the next complete graph containing all the data series currently in memory, writing the PostScript file describing it to disk. The file is usually named mypost; you can set a different name with output. Unless a save command has been used, the plotted series are the ones read in since the last plot command or, if this is the first such command, all the series.
The very first plot of a series can be positioned as shown in the first form of the command: top at the top of the page; center in the middle; bottom at the bottom. The plot will be centered left-right, unless left is included, in which case it will be left justified. If the first plot command is issued without positioning parameters it will fall at the bottom centered left-right. The paper size is assumed to be 8.5 by 11 inches.
Subsequent graphs can be positioned relative to earlier ones by using the second form of plot in the obvious way. The option top will bring the current plot to the top of the page to the right of all earlier plots; center, bottom will be ignored after the first graph. If a second or later plot command is issued without parameters, the graph will appear below the previous plot if the first plot was at the top of the page, above it otherwise.
If these arrangements are insufficient, you can take complete control of positioning by specifying coordinates x0, y0 (inches) of the plot origin, which for these purposes is the place where the annotated axes cross, not the point (0, 0). The coordinates refer to the bottom left corner of the paper with abs. Omitting abs implies relative positioning: that is, x0, y0 is the position of the new plot relative to the previous origin. The option abs is implicit in the first use of plot.
All graphs will be drawn on the same physical page. To get a second
page you must make another plot file with output.
Blank command field: bottom
Performs the reading of the file according to the specifications in
force at this point; see mode. Each read instruction is
performed with a single Fortran READ statement with an implied DO.
This means in mode 2 consecutive points are allowed to run
across a line as x1 y1 x2 y2 x3 y3 ... ; and similarly in modes 1
and 3. With binary files only one binary record is read with every
read command. The integer n is the number of points to be read
from the file, but if n is absent the file is read to the end of file
(eof). When the eof is not reached, the file remains open and ready
for further reading beginning at the next unread record (that is,
the next line in ASCII files); if the eof was reached, another read
on this file will begin at the beginning. Up to 500 separate data
series may be present at any one time. Note that n must be explicit
if file = *
Blank command field: read to end of file
Normally when new points are read after a plot command, the data values for the previous graph are erased. To prevent this, the command save must be entered before the next read statement; then the old and the new data are plotted together on the new graph. If no new data are to be read in, there is no need to use save since the earlier data are retained for plotting in this case.
Decides whether continuous curves of y against x are interpolated
with straight lines, smooth off, or natural cubic splines,
natural, or Akima splines with akima. Akima splines are
piecewise cubic curves with less overshoot than natural splines.
When splines are used, the series is taken to be a single-valued
function of x and the actual x values are re-ordered to be increasing
by plotxy if necessary. Also see NOTES 2. This command
is an input attribute, applying to subsequent read commands,
not to the whole plot. Smooth cancels a symbol command
and vice versa. Smooth off reverts to symbol mode
if that was the previous style of plotting, with the same symbol
number and height as before. Note the automatic plot limits use
the original data series, not the smoothed values, so that sometimes
pieces of a smoothed curve may be lost off the top or bottom
of a graph even when you have let plotxy find its own limits.
The command field may be abbreviated to the first two letters.
Default: off
Blank command field: natural
Skips the next n records in the current data file. With normal ASCII
files this means skipping n lines. The command examines the current
format to determine whether the current file is binary or ASCII.
Blank command field: n = 1
Lists a synopsis of the current data series (their lengths, extreme values and other attributes), the plot and reading parameters, and the memory available for further data series. Also lists some program array limitations of the current version of plotxy.
Closes the output file and brings plotxy to an orderly halt. This must always be the last command of any run from a terminal, otherwise part of your plot may be lost. Stop may be omitted if plotxy is running from a script, since the end-of-file tells the program input is finished.
symbol n [h]
symbol [filled/solid] name [h]
Specifies that the next input series be a set of discrete points designated by symbols of height h, rather than a line. In the first form the kind of symbol is defined by the integer n.
tab(;) center;
llll.
0 square; 8 upward arrow; 17 circle;
1 triangle; 9 hourglass; 22 dash;
2 octagon; 10 campstool; 23 pentagram;
3 diamond; 11 hexagon; 24 pentangle;
4 plus; 12 Y;
5 asterisk; 13 vertical bar;
6 cross; 14 star of David;
7 barred square; 15 dot
Missing integers in the list refer to obsolete entries. The more common symbols can be referenced by name instead of the integer code: asterisk, circle, cross, diamond, dot, hexagon, octagon, plus, square, star, triangle, and pentagram. The objects drawn are outlines; solid symbols are obtained from this list by prepending filled or solid, as in filled circle or solid hexagon.
The approximate height each of symbol is h inches. Negative h causes the symbol to be drawn upside down, useful for triangle and arrow. If h is omitted, the value from the previous symbol command is inherited. The size can be variable, set through the third column in mode input; see below.
To revert to previous line style, use symbol off.
To cause one of these symbols to be drawn in a text string (a note for example) just enclose the symbol number plus 2000 in backslashes, for example, \2017\ for a circle. Add 2050 for a filled symbol.
To plot a series of a single kind of symbol which varies in size,
you must combine symbol with mode 3 or 30; as the mode
number suggests, three values are then read for each input point.
Then, provided h in the symbol command is set greater than or
equal to 10, the three numbers on each line of the file are read
as x, y, z, where z is the symbol height in inches.
Default: n = -1, h = 0.15
Provides a title for the plot. This may be up to 115 characters in
length. A blank command field cancels the previous title and leaves
the next plot untitled. The character font of the title is assumed
by all the lettering of the graph unless explicitly reset. If the
title comprises a font-setting phrase, that sets the font for the
rest of the graph and the graph is untitled.
Default: text = blanks
Specifies a label to be written centered below the x axis. See
title for other details.
Default: text = blanks
xlimit xlength [x1 x2]
xlimit xlength [x1 x2 dx]
xlimit
Defines the length of the x axis, xlength, in inches and the lower and upper limits of x: x1, x2. Only points lying inside (x1, x2) are plotted; those outside are omitted from the plot. If x1 = x2 = 0, or if these values are omitted in the command, the x extremes are chosen to encompass all the values in the data series (autoscaling). If x2 is less than x1 the data and axes are plotted reversed, that is, with x decreasing to the right, between the given limits. Reversed logarithmic axes are not permitted. This is a plot attribute, governing the behavior when plot is invoked.
When the fourth argument, dx, is supplied, tick marks and numbers are written at integer multiples of dx, provided this results in a reasonable quantity of them; otherwise, the defaults are invoked. With log axes, dx has no effect except when it is set negative, and then tick marks between powers of ten are suppressed.
If the command is given with a blank field, the current plot retains the same x axis attributes and scaling as those in the previous graph. Simply omitting the command has the same effect, except when the prior plot was auto-scaled; now that scaling continues to apply, rather than a new one based on the current data.
The default behavior for plot size is somewhat complex: if the x
and y variables cover similar intervals (within a factor of two),
the default height and width are arranged to be in the proportions
of the data, thus giving the same scales for the x and y variables.
Otherwise the height and width are both 3 inches.
Default: xlength = 3, x1 = x2 = 0
Blank command field: retain attributes of the previous plot
Same as xlabel but for the y axis.
Default: text = blanks
Same as xlimit but for the y axis.
Default: ylength = 3, y1 = y2 = 0
Blank command field: retain attributes of the previous plot
This command controls the weight of plotted lines by giving the integer
w, the line thickness in one-thousandths of an inch. Optionally,
lines and points on the graph can be given a different (usually
heavier) weight from text and other material; this is set in wlines.
Invoking weight with only one parameter implicitly sets wlines=w
for subsequent input data.
Default: w = 6, wlines = 12
Blank command field: restore default
DEFAULT VALUES
See NOTES 10 for the way to change these.
Plotxy provides four fonts in which the title, labels, notes may
be written as well as the ability to include mathematical material
and Greek letters. The names of the fonts are simplex,
complex, italic, duplex; the default is complex.
To get any of the others in a text string enclose the first three
letters of the font name in backslashes (e.g. \ita\ or \dup\)
ahead of the text. The font remains in force until explicitly
changed. To obtain a uniform font throughout the graph and
its labels include a font-setting phrase (e.g.\ita\) at the
beginning of title. If you want to vary the fonts within
one plot you can specify the desired font changes in the text; font
changes may appear at any point in a piece of text. There is also a
math font obtained by: \ \. In it letters are set in italics, while
all other characters retain the previous font setting. The math state
toggles to and fro, so that \ \x=y\ \ will be set in italics in
a line set in some other font. Math mode ends with the end of the
text line (unlike other font changes). Note: plotxy draws
its own letters as a set of lines, and does not use PostScript fonts.
You may also get Greek letters by enclosing their names in backslashes,
as \GAMMA\ or \lambda\; upper case Greek appears when the English
name is upper case. The name of a Greek letter can be abbreviated to
its fewest unambiguous leading letters: thus \s\ specifies sigma, but
you need \ome\ for omega. The default theta and phi characters are
the flowery script versions: to get plain ones type: \rgtheta\ and
\rgphi\, for regular theta and phi. Superscripts are possible with
the construct \sup{...}, so that x-squared is rendered x\sup{2}.
Similarly with subscripts one writes, for example, g\sub{ij}.
As mentioned in symbol you may plot a special graphics symbol
by enclosing the symbol integer plus 2000 in backslashes. The code
\bs\ suppresses the character advance so that characters may be
superimposed. Characters may be embellished with a hat \ˆ\, or a
tilde \˜\, or a an overbar \-\. The code follows the decorated
letter: x\-\ for example.
There are some characters with no keyboard equivalent. Some of them
can be specified by their names enclosed in backslashes; these may
always be shortened to the first 4 letters. Here are the special
characters for which this is permitted:
There are other, perhaps more obscure, symbols that you can access only
with numerical codes: a 4-digit key number enclosed in backslashes.
Here is a table of the codes for these special symbols; curly braces
can be accessed only through their 4-digit codes, not the characters
on the keyboard. Astronomical symbols generously provided by Duncan
Agnew.
Finally, another use for the numerical code is to specify text size:
the height of the text following the phrase \0.25\ is changed
from its current value to 0.25 inches; any number less than 5 is
interpreted as the letter height in inches. The values are rounded
to hundredths of an inch. Letter heights defined in this way hold
only for the note or other text in which they appear, subsequent
material reverts to the size set by default or character.
1. Plotxy is reasonably graceful with error conditions:
explanatory messages are issued in most circumstances. The messages
are usually in two parts: what went wrong and what plotxy has
done about it. For example, if unintelligible data are encountered,
plotxy will reject the whole series and then issue a warning.
Attempting to plot negative data on a log scale generates an error
message and the offending scale is made linear instead of logarithmic,
unless the logy+ option has been selected in logxy.
2. When smooth is used, the data series is re-ordered if
necessary to make x increase; repeated x-values will turn off
smoothing, and the re-ordered series are drawn joined by straight-line
segments.
3. If plot extremes have been set with xlimit or ylimit
and a data value falls outside the window, the result depends on
whether smoothing has been set. Without smoothing, the virtual
"pen" is simply lifted until onscale data are encountered again.
This allows you to insert breaks in your data records by inserting
large values; but remember to set limits explicitly before plot.
When smooth is on, plotxy draws a piece of curve between
the last captured point(s) and the edge of the graph in the direction
of the exterior point.
4. To plot a line with symbols at the coordinates, read the data file
twice, once with an interpolating line and then with symbol.
Lines with both long and short dashes can be drawn by entering
four values in the dash command.
5. The sizes of the arrow heads can be controlled: they are
proportional to the current symbol height set with character.
If you would like a larger arrow head with regular size text in a note,
you can regulate the text height with a size phrase, like \0.10\.
6. Any piece of text may be preceded by a font phrase; its height may
be specified either by the character command, or as described
in the previous section. To arrange a special font for the axes
numerals put the font phrase at the end of the title.
7. Reversing x and y axes (as when coordinates are specified as
latitude and longitude) is easily done with mode 20:
mode 20 2 1
8. Plotxy is written almost entirely with single-precision
(real*4) variables. If data are to be plotted in which the only
variation occur in the seventh (or later) significant figure, there
will be inaccuracies. One solution (other than recompilation) is
to subtract a constant value from the data values before plotting to
map them into a more manageable interval.
9. The preset defaults may not be to the user's taste. Finding and
replacing them in the code would be tedious. Instead, the last
subroutine, 'dfault', executes commands internally before plotxy
reads from the command line. Preferred defaults, such as font,
letter height, background color, etc can be set there, and will
override the defaults given in the documentation.
10. Sometimes data are best displayed as symbols on top of a
vertical stalk that extends to zero. Obviously a special data
file could be prepared to do this, but here is simple
alternative: first, create a data file with x,y,0, one triplet per
line. Then this plot script will display the series with a filled
square atop a stalk:
feet 0 % Erase feet from error bars
11. There is one special filename for read, the letter O. This
creates an internal `file' usually with 361 lines comprising x-y pairs,
cos(n-1)a, sin(n-1)a, where a is one degree, defining an
approximate unit circle centered on the origin. Read to the end,
O will produce a unit circle, which can be displaced and scaled or
stretched with affine if desired. Arcs of a circle can be made
by skipping and reading the required portion of the whole. Thus
file O
12. Mode 3 reads with 4 columns, used to specify asymmetric
error bars, can be adapted to several other uses. For example,
a filled region can be built by giving in tabular form x and its
upper and lower boundaries at that x. Then
fill
affine 1, 0, 1, 0 output mypost
character 0.08, 0 smooth off
dash 0, 0 symbol off 0
file * title blanks
format * xlabel blanks
frame off xlimit 3, 0, 0
logxy 0 ylabel blanks
mode 2 ylimit 3, 0, 0
weight 6, 12
gradient, integral, infinity, times, partial derivative, degree.
For square root, use \sqrt\.
center;
lll.
1387 partial d 1403 summation 1439 Venus
1388 grad 1404 regular theta 1440 Earth
1389 member of 1405 { 1441 Mars
1390 less or equal 1406 } 1442 Jupiter
1391 greater or equal 1412 paragraph 1443 Saturn
1392 proportional 1413 dagger 1444 Uranus
1393 integral 1425 tall < 1445 Nepture
1394 circuit int 1426 tall > 1446 Pluto
1395 infinity 1429 degree 1447 crescent moon
1396 + or - 1430 tends to 1448 comet
1397 - or + 1431 regular phi 1450 Aries
1398 times 1434 not equal
1399 division 1435 approximates
1400 product 1436 shah
1401 times dot 1437 Sun
1402 radical 1438 Mercury
read
symbol filled square 0.06 % Plot a square at (x,y)
file data
mode 30 1 2 2 3 % Treat data as asymmetric error bar
read % between 0 and y
skip 90
read 91
mode 3 1 2 3 3
read