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fplot

Plot symbolic expression or function

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Syntax

fplot(f)
fplot(f,[xmin xmax])
fplot(xt,yt)
fplot(xt,yt,[tmin tmax])
fplot(___,LineSpec)
fplot(___,Name,Value)
fplot(ax,___)
fp = fplot(___)

Description

fplot(f) plots symbolic input f over the default interval [-5 5].

example

fplot(f,[xmin xmax]) plots f over the interval [xmin xmax].

example

fplot(xt,yt) plots xt = x(t) and yt = y(t) over the default range of t, which is [–5 5].

example

fplot(xt,yt,[tmin tmax]) plots xt = x(t) and yt = y(t) over the specified range [tmin tmax].

fplot(___,LineSpec) uses LineSpec to set the line style, marker symbol, and line color.

example

fplot(___,Name,Value) specifies line properties using one or more Name,Value pair arguments. Use this option with any of the input argument combinations in the previous syntaxes. Name,Value pair settings apply to all the lines plotted. To set options for individual lines, use the objects returned by fplot.

example

fplot(ax,___) plots into the axes specified by ax instead of the current axes gca.

fp = fplot(___) returns a function line object or parameterized line object, depending on the type of plot. Use the object to query and modify properties of a specific line. For details, see FunctionLine Properties and ParameterizedFunctionLine Properties.

example

Examples

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Open Live Script

Plot tan(x) over the default range [-5 5]. fplot shows poles by default. For details, see the ShowPoles argument in Name-Value Arguments.

syms x
fplot(tan(x))

Figure contains an axes object. The axes object contains an object of type functionline.

Open Live Script

Plot the symbolic function f(x) = cos(x) over the default range [-5 5].

syms f(x)
f(x) = cos(x);
fplot(f)

Figure contains an axes object. The axes object contains an object of type functionline.

Open Live Script

Plot the parametric curve x = cos(3*t) and y = sin(2*t).

syms t
x = cos(3*t);
y = sin(2*t);
fplot(x,y)

Figure contains an axes object. The axes object contains an object of type parameterizedfunctionline.

Open Live Script

Plot sin(x) over [-pi/2 pi/2] by specifying the plotting interval as the second input to fplot.

syms x
fplot(sin(x),[-pi/2 pi/2])

Figure contains an axes object. The axes object contains an object of type functionline.

Open Live Script

You can plot multiple lines either by passing the inputs as a vector or by using hold on to successively plot on the same figure. If you specify LineSpec and Name-Value arguments, they apply to all lines. To set options for individual plots, use the function handles returned by fplot.

Divide a figure into two subplots using subplot. On the first subplot, plot sin(x) and cos(x) using vector input. On the second subplot, plot sin(x) and cos(x) using hold on.

syms x
subplot(2,1,1)
fplot([sin(x) cos(x)])
title('Multiple Lines Using Vector Inputs')

subplot(2,1,2)
fplot(sin(x))
hold on
fplot(cos(x))
title('Multiple Lines Using hold on Command')

hold off

Figure contains 2 axes objects. Axes object 1 with title Multiple Lines Using Vector Inputs contains 2 objects of type functionline. Axes object 2 with title Multiple Lines Using hold on Command contains 2 objects of type functionline.

Open Live Script

Plot three sine curves with a phase shift between each line. For the first line, use a linewidth of 2. For the second, specify a dashed red line style with circle markers. For the third, specify a cyan, dash-dot line style with asterisk markers. Display the legend.

syms x
fplot(sin(x+pi/5),'Linewidth',2)
hold on
fplot(sin(x-pi/5),'--or')
fplot(sin(x),'-.*c')
legend('show','Location','best')
hold off

Figure contains an axes object. The axes object contains 3 objects of type functionline.

Open Live Script

Control the resolution of a plot by using the MeshDensity option. Increasing MeshDensity can make smoother, more accurate plots, while decreasing it can increase plotting speed.

Divide a figure into two by using subplot. In the first subplot, plot a step function from x = 2.1 to x = 2.15. The plot's resolution is too low to detect the step function. Fix this issue by increasing MeshDensity to 39 in the second subplot. The plot now detects the step function and shows that by increasing MeshDensity you increased the plot's resolution.

syms x
stepFn = rectangularPulse(2.1, 2.15, x);

subplot(2,1,1)
fplot(stepFn);
title('Default MeshDensity = 23')

subplot(2,1,2)
fplot(stepFn,'MeshDensity',39);
title('Increased MeshDensity = 39')

Figure contains 2 axes objects. Axes object 1 with title Default MeshDensity = 23 contains an object of type functionline. Axes object 2 with title Increased MeshDensity = 39 contains an object of type functionline.

Open Live Script

Plot sin(x). Specify an output to make fplot return the plot object.

syms x
h = fplot(sin(x))

Figure contains an axes object. The axes object contains an object of type functionline.

h = 
  FunctionLine with properties:

     Function: sin(x)
        Color: [0 0.4470 0.7410]
    LineStyle: '-'
    LineWidth: 0.5000

  Use GET to show all properties

Change the default blue line to a dashed red line by using dot notation to set properties. Similarly, add 'x' markers and set the marker color to blue.

h.LineStyle = '--';
h.Color = 'r';
h.Marker = 'x';
h.MarkerEdgeColor = 'b';

Figure contains an axes object. The axes object contains an object of type functionline.

Open Live Script

Plot sin(x) over the interval [-2*pi 2*pi]. Add a title and axis labels. Create the x-axis ticks by spanning the x-axis limits at intervals of pi/2. Display these ticks by using the XTick property. Create x-axis labels by using arrayfun to apply texlabel to S. Display these labels by using the XTickLabel property.

To use LaTeX in plots, see latex.

syms x
fplot(sin(x),[-2*pi 2*pi])
grid on
title('sin(x) from -2\pi to 2\pi')
xlabel('x')
ylabel('y')

ax = gca;
S = sym(ax.XLim(1):pi/2:ax.XLim(2));
ax.XTick = double(S);
ax.XTickLabel = arrayfun(@texlabel,S,'UniformOutput',false);

Figure contains an axes object. The axes object with title sin(x) blank from blank - 2 pi blank to blank 2 pi, xlabel x, ylabel y contains an object of type functionline.

Open Script

When you zoom into a plot, fplot reevaluates the plot automatically. The reevaluation when zooming reveals more details at smaller scales.

Plot the curve $y = x^3 \sin(1/x)$ for $-2 < x < 2$ and $-0.02 < y < 0.02$. Zoom into the plot using zoom and redraw the plot using drawnow. Because of reevaluation on zoom, fplot reveals more details. Repeat the zoom 6 times to view smaller-scale details.

syms x
fplot(x^3*sin(1/x));
axis([-2 2 -0.02 0.02]);
for i=1:6
    zoom(1.7)
    pause(0.5)
end

Open Script

Create an animation of a parametric curve where one of the parameters changes with time. The $x$- and $y$-coordinates of the parametric curve are given by

$$x = k t \sin(k t)$$

$$y = k t \cos(k t).$$

By varying the variable $t$ from 0.1 to 3, animate the parametric curve.

Create two symbolic variables k and t. Use the variable k to parameterize the curve within the range [-5 5] and use the variable t to animate the curve as the time proceeds from 0.1 to 3. Create a stop-motion animation object of the time snapshots by using fanimator. Set the $x$-axis and $y$-axis to be equal length.

syms k t
fanimator(@fplot,k*t*sin(k*t),k*t*cos(k*t),[-5 5],AnimationRange = [0.1 3])
axis equal

Play the animation by using playAnimation.

playAnimation

You can also save the animation as a GIF file by using writeAnimation.

writeAnimation("parametricCurve.gif")

Input Arguments

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Expression or function to plot, specified as a symbolic expression or function.

Plotting interval for x-coordinates, specified as a vector of two numbers. The default range is [-5 5]. However, if fplot detects a finite number of discontinuities in f, then fplot expands the range to show them.

Parametric input for x-coordinates, specified as a symbolic expression or function. fplot uses symvar to find the parameter.

Parametric input for y-axis, specified as a symbolic expression or function. fplot uses symvar to find the parameter.

Range of values of parameter t, specified as a vector of two numbers. The default range is [-5 5].

Axes object. If you do not specify an axes object, then fplot uses the current axes gca.

Line style, marker, and color, specified as a string scalar or character vector containing symbols. The symbols can appear in any order. You do not need to specify all three characteristics (line style, marker, and color). For example, if you omit the line style and specify the marker, then the plot shows only the marker and no line.

Example: "--or" is a red dashed line with circle markers.

Line StyleDescriptionResulting Line
"-"Solid line

Sample of solid line

"--"Dashed line

Sample of dashed line

":"Dotted line

Sample of dotted line

"-."Dash-dotted line

Sample of dash-dotted line, with alternating dashes and dots

MarkerDescriptionResulting Marker
"o"Circle

Sample of circle marker

"+"Plus sign

Sample of plus sign marker

"*"Asterisk

Sample of asterisk marker

"."Point

Sample of point marker

"x"Cross

Sample of cross marker

"_"Horizontal line

Sample of horizontal line marker

"|"Vertical line

Sample of vertical line marker

"square"Square

Sample of square marker

"diamond"Diamond

Sample of diamond marker

"^"Upward-pointing triangle

Sample of upward-pointing triangle marker

"v"Downward-pointing triangle

Sample of downward-pointing triangle marker

">"Right-pointing triangle

Sample of right-pointing triangle marker

"<"Left-pointing triangle

Sample of left-pointing triangle marker

"pentagram"Pentagram

Sample of pentagram marker

"hexagram"Hexagram

Sample of hexagram marker

Color NameShort NameRGB TripletAppearance
"red""r"[1 0 0]

Sample of the color red

"green""g"[0 1 0]

Sample of the color green

"blue""b"[0 0 1]

Sample of the color blue

"cyan" "c"[0 1 1]

Sample of the color cyan

"magenta""m"[1 0 1]

Sample of the color magenta

"yellow""y"[1 1 0]

Sample of the color yellow

"black""k"[0 0 0]

Sample of the color black

"white""w"[1 1 1]

Sample of the color white

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: 'Marker','o','MarkerFaceColor','red'

The function line properties listed here are only a subset. For a complete list, see FunctionLine Properties.

Number of evaluation points, specified as a number. The default is 23. Because fplot uses adaptive evaluation, the actual number of evaluation points is greater.

Display asymptotes at poles, specified as 'on' or 'off', or as numeric or logical 1 (true) or 0 (false). A value of 'on' is equivalent to true, and 'off' is equivalent to false. Thus, you can use the value of this property as a logical value. The value is stored as an on/off logical value of type matlab.lang.OnOffSwitchState.

The asymptotes display as gray, dashed vertical lines. fplot displays asymptotes only with the fplot(f) syntax or variants, and not with the fplot(xt,yt) syntax.

Line color, specified as an RGB triplet, a hexadecimal color code, a color name, or a short name.

For a custom color, specify an RGB triplet or a hexadecimal color code.

  • An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1], for example, [0.4 0.6 0.7].

  • A hexadecimal color code is a string scalar or character vector that starts with a hash symbol (#) followed by three or six hexadecimal digits, which can range from 0 to F. The values are not case sensitive. Therefore, the color codes "#FF8800", "#ff8800", "#F80", and "#f80" are equivalent.

Alternatively, you can specify some common colors by name. This table lists the named color options, the equivalent RGB triplets, and hexadecimal color codes.

Color NameShort NameRGB TripletHexadecimal Color CodeAppearance
"red""r"[1 0 0]"#FF0000"

Sample of the color red

"green""g"[0 1 0]"#00FF00"

Sample of the color green

"blue""b"[0 0 1]"#0000FF"

Sample of the color blue

"cyan" "c"[0 1 1]"#00FFFF"

Sample of the color cyan

"magenta""m"[1 0 1]"#FF00FF"

Sample of the color magenta

"yellow""y"[1 1 0]"#FFFF00"

Sample of the color yellow

"black""k"[0 0 0]"#000000"

Sample of the color black

"white""w"[1 1 1]"#FFFFFF"

Sample of the color white

Here are the RGB triplets and hexadecimal color codes for the default colors MATLAB® uses in many types of plots.

RGB TripletHexadecimal Color CodeAppearance
[0 0.4470 0.7410]"#0072BD"

Sample of RGB triplet [0 0.4470 0.7410], which appears as dark blue

[0.8500 0.3250 0.0980]"#D95319"

Sample of RGB triplet [0.8500 0.3250 0.0980], which appears as dark orange

[0.9290 0.6940 0.1250]"#EDB120"

Sample of RGB triplet [0.9290 0.6940 0.1250], which appears as dark yellow

[0.4940 0.1840 0.5560]"#7E2F8E"

Sample of RGB triplet [0.4940 0.1840 0.5560], which appears as dark purple

[0.4660 0.6740 0.1880]"#77AC30"

Sample of RGB triplet [0.4660 0.6740 0.1880], which appears as medium green

[0.3010 0.7450 0.9330]"#4DBEEE"

Sample of RGB triplet [0.3010 0.7450 0.9330], which appears as light blue

[0.6350 0.0780 0.1840]"#A2142F"

Sample of RGB triplet [0.6350 0.0780 0.1840], which appears as dark red

Example: "blue"

Example: [0 0 1]

Example: "#0000FF"

Line style, specified as one of the options listed in this table.

Line StyleDescriptionResulting Line
"-"Solid line

Sample of solid line

"--"Dashed line

Sample of dashed line

":"Dotted line

Sample of dotted line

"-."Dash-dotted line

Sample of dash-dotted line, with alternating dashes and dots

"none"No lineNo line

Line width, specified as a positive value in points, where 1 point = 1/72 of an inch. If the line has markers, then the line width also affects the marker edges.

The line width cannot be thinner than the width of a pixel. If you set the line width to a value that is less than the width of a pixel on your system, the line displays as one pixel wide.

Marker symbol, specified as one of the values listed in this table. By default, the object does not display markers. Specifying a marker symbol adds markers at each data point or vertex.

MarkerDescriptionResulting Marker
"o"Circle

Sample of circle marker

"+"Plus sign

Sample of plus sign marker

"*"Asterisk

Sample of asterisk marker

"."Point

Sample of point marker

"x"Cross

Sample of cross marker

"_"Horizontal line

Sample of horizontal line marker

"|"Vertical line

Sample of vertical line marker

"square"Square

Sample of square marker

"diamond"Diamond

Sample of diamond marker

"^"Upward-pointing triangle

Sample of upward-pointing triangle marker

"v"Downward-pointing triangle

Sample of downward-pointing triangle marker

">"Right-pointing triangle

Sample of right-pointing triangle marker

"<"Left-pointing triangle

Sample of left-pointing triangle marker

"pentagram"Pentagram

Sample of pentagram marker

"hexagram"Hexagram

Sample of hexagram marker

"none"No markersNot applicable

Marker outline color, specified as "auto", an RGB triplet, a hexadecimal color code, a color name, or a short name. The default value of "auto" uses the same color as the Color property.

For a custom color, specify an RGB triplet or a hexadecimal color code.

  • An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1], for example, [0.4 0.6 0.7].

  • A hexadecimal color code is a string scalar or character vector that starts with a hash symbol (#) followed by three or six hexadecimal digits, which can range from 0 to F. The values are not case sensitive. Therefore, the color codes "#FF8800", "#ff8800", "#F80", and "#f80" are equivalent.

Alternatively, you can specify some common colors by name. This table lists the named color options, the equivalent RGB triplets, and hexadecimal color codes.

Color NameShort NameRGB TripletHexadecimal Color CodeAppearance
"red""r"[1 0 0]"#FF0000"

Sample of the color red

"green""g"[0 1 0]"#00FF00"

Sample of the color green

"blue""b"[0 0 1]"#0000FF"

Sample of the color blue

"cyan" "c"[0 1 1]"#00FFFF"

Sample of the color cyan

"magenta""m"[1 0 1]"#FF00FF"

Sample of the color magenta

"yellow""y"[1 1 0]"#FFFF00"

Sample of the color yellow

"black""k"[0 0 0]"#000000"

Sample of the color black

"white""w"[1 1 1]"#FFFFFF"

Sample of the color white

"none"Not applicableNot applicableNot applicableNo color

Here are the RGB triplets and hexadecimal color codes for the default colors MATLAB uses in many types of plots.

RGB TripletHexadecimal Color CodeAppearance
[0 0.4470 0.7410]"#0072BD"

Sample of RGB triplet [0 0.4470 0.7410], which appears as dark blue

[0.8500 0.3250 0.0980]"#D95319"

Sample of RGB triplet [0.8500 0.3250 0.0980], which appears as dark orange

[0.9290 0.6940 0.1250]"#EDB120"

Sample of RGB triplet [0.9290 0.6940 0.1250], which appears as dark yellow

[0.4940 0.1840 0.5560]"#7E2F8E"

Sample of RGB triplet [0.4940 0.1840 0.5560], which appears as dark purple

[0.4660 0.6740 0.1880]"#77AC30"

Sample of RGB triplet [0.4660 0.6740 0.1880], which appears as medium green

[0.3010 0.7450 0.9330]"#4DBEEE"

Sample of RGB triplet [0.3010 0.7450 0.9330], which appears as light blue

[0.6350 0.0780 0.1840]"#A2142F"

Sample of RGB triplet [0.6350 0.0780 0.1840], which appears as dark red

Marker fill color, specified as "auto", an RGB triplet, a hexadecimal color code, a color name, or a short name. The "auto" value uses the same color as the MarkerEdgeColor property.

For a custom color, specify an RGB triplet or a hexadecimal color code.

  • An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1], for example, [0.4 0.6 0.7].

  • A hexadecimal color code is a string scalar or character vector that starts with a hash symbol (#) followed by three or six hexadecimal digits, which can range from 0 to F. The values are not case sensitive. Therefore, the color codes "#FF8800", "#ff8800", "#F80", and "#f80" are equivalent.

Alternatively, you can specify some common colors by name. This table lists the named color options, the equivalent RGB triplets, and hexadecimal color codes.

Color NameShort NameRGB TripletHexadecimal Color CodeAppearance
"red""r"[1 0 0]"#FF0000"

Sample of the color red

"green""g"[0 1 0]"#00FF00"

Sample of the color green

"blue""b"[0 0 1]"#0000FF"

Sample of the color blue

"cyan" "c"[0 1 1]"#00FFFF"

Sample of the color cyan

"magenta""m"[1 0 1]"#FF00FF"

Sample of the color magenta

"yellow""y"[1 1 0]"#FFFF00"

Sample of the color yellow

"black""k"[0 0 0]"#000000"

Sample of the color black

"white""w"[1 1 1]"#FFFFFF"

Sample of the color white

"none"Not applicableNot applicableNot applicableNo color

Here are the RGB triplets and hexadecimal color codes for the default colors MATLAB uses in many types of plots.

RGB TripletHexadecimal Color CodeAppearance
[0 0.4470 0.7410]"#0072BD"

Sample of RGB triplet [0 0.4470 0.7410], which appears as dark blue

[0.8500 0.3250 0.0980]"#D95319"

Sample of RGB triplet [0.8500 0.3250 0.0980], which appears as dark orange

[0.9290 0.6940 0.1250]"#EDB120"

Sample of RGB triplet [0.9290 0.6940 0.1250], which appears as dark yellow

[0.4940 0.1840 0.5560]"#7E2F8E"

Sample of RGB triplet [0.4940 0.1840 0.5560], which appears as dark purple

[0.4660 0.6740 0.1880]"#77AC30"

Sample of RGB triplet [0.4660 0.6740 0.1880], which appears as medium green

[0.3010 0.7450 0.9330]"#4DBEEE"

Sample of RGB triplet [0.3010 0.7450 0.9330], which appears as light blue

[0.6350 0.0780 0.1840]"#A2142F"

Sample of RGB triplet [0.6350 0.0780 0.1840], which appears as dark red

Example: [0.3 0.2 0.1]

Example: "green"

Example: "#D2F9A7"

Marker size, specified as a positive value in points, where 1 point = 1/72 of an inch.

Output Arguments

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One or more function or parameterized function line objects, returned as a scalar or a vector.

  • If you use the fplot(f) syntax or a variation of this syntax, then fplot returns function line objects.

  • If you use the fplot(xt,yt) syntax or a variation of this syntax, then fplot returns parameterized line objects.

You can use these objects to query and modify properties of a specific line. For a list of properties, see FunctionLine Properties and ParameterizedFunctionLine Properties.

Tips

  • If fplot detects a finite number of discontinuities in f, then fplot expands the range to show them.

  • If fplot is used with a function handle to a named or anonymous function (that is not a symbolic expression or function), then the MATLAB fplot function is called. In this case, the function handle must accept a vector input argument and return a vector output argument of the same size. Use array operators instead of matrix operators for the best performance. For example, use .* (times) instead of * (mtimes) in the code fplot(@(x) x.*sin(2*pi*x)).

Version History

Introduced in R2016a

See Also

Functions

Properties

Topics