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plot

create a two-dimensional plot of functions

 

Calling Sequence

Parameters

Basic Information

Description

Options

Notes

Examples

Calling Sequence

plot(expr, x=a..b, opts)

plot(f, a..b, opts)

plot([expr1, expr2, t=c..d], opts)

plot([f1, f2, c..d], opts)

plot(m, opts)

plot(v1, v2, opts)

Parameters

expr

-

expression in x

expr1, expr2

-

expressions in t

f, f1, f2

-

procedure or operators

x, t

-

names

a, b, c, d

-

real constants

m

-

Matrix or list of lists

v1, v2

-

Vectors or lists

opts

-

optional arguments as described in the Options section

Basic Information

• 

This help page contains complete information about the plot command. For basic information on the plot command, see the plot help page.

Description

• 

The plot command is used to generate a curve from a function or a set of points in a 2-D plot.  If a function is provided, it may be specified as an expression in the plotting variable or as a procedure; alternatively, a parametric form of the function may be provided.

Plotting from an Expression or Procedure

• 

The most common way to use the plot command is to use the first calling sequence, plot(expr, x=a..b), where an expression in one variable is specified over a given range on the horizontal axis. An example is plot(u^2-5, u=-2..3).

• 

The second calling sequence is in operator form.  This allows you to use a procedure or operator to specify the function to be plotted.  The second argument, if given, must be a range; note that no variable name is used with operator form.  An example is plot(sin, -Pi..Pi).

• 

With both calling sequences, if the range is not provided, the default range is 2π..2π for trigonometric functions and 10..10 otherwise.  For more information about plot ranges, see the plot[range] help page. For more details about plotting functions, see the plot[function] help page.

Using the Parametric Form

• 

In the third calling sequence, plot([expr1, expr2, t=c..d]), the function is specified in parametric form.  The first argument is a list having three components: an expression for the x-coordinate, an expression for the y-coordinate, and the parameter range. For example, to plot a circle, use plot([sin(t), cos(t), t=0..2*Pi]).

• 

The fourth calling sequence shows the operator-form of a parametric plot. Here, the first argument is a list containing two procedures or operators, specifying the x- and y-coordinates respectively, and a range.  For example, to plot a circle, use plot([sin, cos, 0..2*Pi]).

• 

For more information about parametric plots, see the plot[parametric] help page.

Plotting from Points

• 

The last two calling sequences are for generating a curve from n points. In the calling sequence plot(m), m is an n by 2 Matrix or a list of n 2-component lists [u, v].  An example is plot([[0, 1], [1, 2], [2, 5], [3, 8]]).

• 

In the calling sequence plot(v1, v2), v1 and v2 are two n-dimensional Vectors or two lists containing n numerical values.  They correspond to the x-coordinates and y-coordinates respectively.  An example is plot(Vector([0, 1, 2, 3]), Vector([1, 2, 5, 8])).

• 

The Matrix, Vector and list entries must all be real constants.  By default, a line going through the given points is generated. If you wish to see points plotted instead of a line, add the style=point option.

Generating Multiple Curves

• 

Multiple curves can be plotted by replacing the first argument with a list or set of items, in every calling sequence except the last. Options such as color or thickness can be specified for each curve by using a list of values as the right-hand side of the option equation. In this situation, the first argument to the plot command must also be a list; if it is a set, the order of the plots might not be preserved.

• 

A default color is assigned to each of the multiple curves. To customize the selection of colors, use the plots[setcolors] command.

Interactive Plotting

• 

Maple includes an Interactive Plot Builder.  Using the plots[interactive] command, you can build plots interactively.  For more information, see plots[interactive] and plotinterface/interactive.

• 

Other interactive plotting commands are available in the Student and Statistics packages.

Options

  

The opts argument shown in the Calling Sequence section above consists of a sequence of one or more plotting options.  The plot command accepts most of the 2-D plotting options described on the plot/options help page.  This section includes a brief summary of commonly used options.  See the plot/options help page for details on usage.

• 

The view option is used to control the horizontal and vertical ranges that are displayed.  By default, the x-range in the calling sequences is used for the horizontal view.  You may optionally provide a y-range following the x-range; this is used for the vertical view but does not affect the values computed.  The scaling option allows you to constrain the scaling of the horizontal and vertical axes so they are equal.

• 

The axes option controls the style of axes displayed.  Further control over the look of each axis is described in the plot/axis help page.  Gridline and tickmark options are described in the plot/tickmarks help page.  The labels option adds axes labels; if this option is not given, the default labels are the names (if provided) associated with the range arguments.

• 

Options that affect the computation of the points that make up a curve include: discont for avoiding points of discontinuity, and numpoints to specify a minimum number of points.  The adaptive, resolution and sample options give additional control over the sampling.

• 

Titles and captions may be added with the title and caption options.

• 

The look of a curve may be controlled with the color, thickness and linestyle options. Additionally, a legend entry may be provided for the curve with the legend option.  A list of values may be given for these options when multiple curves are being plotted.

• 

When plotting points, use the style, symbol and symbolsize options to control the look of the points.

• 

By default, the smartview option is set to true. In some cases, this causes the view of the data to be restricted so that the most important regions of the plot are shown.

• 

Plotting may be done in an alternative coordinate system using the coords option.  For more information, see the plot/coords help page. It is recommended, however, that you use the plots[polarplot] command for plotting with polar coordinates.

Notes

• 

The arguments to the plot function are evaluated numerically, not symbolically.  For more information about the computational environment used by the plot function, see plot[computation].

• 

An empty plot may result if errors occur during the evaluation of the arguments to plot.  Errors generated during the evaluation of functions are replaced with the value undefined to allow the plots system to better handle singularities.

• 

Providing an empty set or list as the first argument also results in an empty plot.

• 

Help pages describing plotting commands and interactive plotting features are written with the assumption that you are using the Standard Worksheet interface.  If you are using a different interface, see plot/interface.

• 

An output device may be specified using the plotsetup command. See plot/device for a list of supported devices.

• 

For three-dimensional plots, see plot3d.  Commands for generating specific types of plots, such as implicitly defined plots and plots on the complex plane, are found in the plots package.  Tools for manipulating plot elements are found in the plottools package.

• 

A call to plot produces a PLOT data structure.  For more information, see plot/structure.

• 

An empty plot can be obtained by providing the empty list as the first argument expr or f in the first two calling sequences, or by omitting expr or f altogether.

Examples

Using an expression to specify function to be plotted

Plot with a specified range:

plotcosx+sinx,x=0..π

Plots without a specified range:

The default range is 2π..2π for trigonometric functions.

plotcosx+sinx

For other functions, such as polynomials, the default range is 10..10.

plotx3+2x2+20

Using a procedure or operator to specify the function to be plotted

With a specified range:

plottan,π..π,discont

Without a specified range:

For trigonometric functions, the default range is 2π..2π.

plottan,discont

For non-trigonometric functions, the default range is 10..10.

plot(proc (x) if x < 2 and -1 < x then x^2 else x+2 end if end proc);

Plots using parametric form

Using expressions to write the functions.

plotsint&comma;cost&comma;t&equals;&pi;..&pi;

plotsint&comma;t

Note: The default range 2π..2π is used for the last example since no range was specified.

 

plotx3&comma;x&comma;x&equals;0..3&pi;&comma;8..8&comma;10..10&comma;coords&equals;polar

 

Using operator-forms.

plotcos&plus;sin&comma;0..&pi;

plottan&comma;&pi;..&pi;&comma;discont

plotsin

plotsin&comma;cos&comma;&pi;..&pi;

Generating multiple curves

Using a list to specify functions to be plotted:

plotsinx&comma;x1x36&comma;x&equals;0..2&comma;color&equals;DarkGreen&comma;NavyBlue&comma;style&equals;point&comma;line

Now, using a set to specify the same functions:

plotx1x36&comma;sinx&comma;x&equals;0..2

Note that using a set to specify the functions might not preserve the order of the plots.

Point plots

ln&comma;sinn&dollar;n&equals;1..10&colon;

plotl&comma;x&equals;0..15&comma;style&equals;point&comma;symbol&equals;circle

 

Alternatively, use the plots[pointplot] command to generate a plot of data points. See plots[pointplot] for more information.

Plots using polar coordinates

Method 1:

st&rarr;100100&plus;t&pi;28&colon;rt&rarr;st2sin7tcos30t2&colon;

plotrt&comma;t&comma;t&equals;&pi;2..3&pi;2&comma;numpoints&equals;2000&comma;coords&equals;polar&comma;axes&equals;none

Method 2:

You can specify thickness of the a plot as well.

plotsin4x&comma;x&comma;x&equals;0..2&pi;&comma;coords&equals;polar&comma;thickness&equals;3

Using various plot options

The second argument opts can be used to add a variety of plot options that are used to customize the plot and axes labels, title, scaling, the look of a curve in terms of its thickness, color, style, and so on. For details, see the Options section.

 

Add a title and axes labels.

plotsinx&comma;cosx&comma;x&equals;&pi;..&pi;&comma;title&equals;A Circle in Cartesian Coordinates

 

The default axes style is called normal. You can change the style to one of framed, boxed, or none.

plotsinx&comma;cosx&comma;x&equals;&pi;..&pi;&comma;axes&equals;framed

 

A multi function plot to demonstrate the color option.

plotsinxcosx&comma;1x25&comma;1x27&comma;x&equals;1&pi;2..1&pi;2&comma;color&equals;Blue&comma;Magenta&comma;Cyan

 

The tickmark option specifies the tickmark placement for the x-axis and y-axis respectively.

plotx&comma;tanx&comma;x&equals;&pi;..&pi;&comma;4..4&comma;5..5&comma;tickmarks&equals;8&comma;10&comma;discont

 

The options demonstrated here are only a few of all that can be applied to the plot command. For a comprehensive list, see plot[options].

Other plots

For expressions having discontinuities over finite intervals use the discont option. See plot[discont] for details.

plottanx&comma;x&equals;2&pi;..2&pi;&comma;y&equals;4..4&comma;discont

 

Compare this to the next example where discont was not used.

plottanx&comma;x&equals;2&pi;..2&pi;&comma;y&equals;4..4

 

Here is another example demonstrating use of the discont option.

plot1&plus;2Heavisidex1&comma;x&equals;1..2&comma;discont

 

Infinity plot.

plotsinx&comma;x&equals;0..&infin;

Empty plots

plot

  

Empty plot with a specified boundary.

plotx&equals;0..2&pi;&comma;axes&equals;boxed

See Also

discont

fdiscont

plot

plot/color

plot/computation

plot/device

plot/discont

plot/function

plot/infinity

plot/interface

plot/multiple

plot/options

plot/parametric

plot/range

plot/structure

plot/style

plot3d

plotinterface/interactive

plots[display]

plots[interactive]

plots[pointplot]

plots[polarplot]

plots[setcolors]

plotsetup

 


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