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fplot

Plot expression or function

Syntax

fplot(f)
fplot(f,xinterval)
fplot(funx,funy)
fplot(funx,funy,tinterval)
fplot(___,LineSpec)
fplot(___,Name,Value)
fplot(ax,___)
fp = fplot(___)
[x,y] = fplot(___)

Description

example

fplot(f) plots the curve defined by the function y = f(x) over the default interval [-5 5] for x.

example

fplot(f,xinterval) plots over the specified interval. Specify the interval as a two-element vector of the form [xmin xmax].

example

fplot(funx,funy) plots the curve defined by x = funx(t) and y = funy(t) over the default interval [-5 5] for t.

fplot(funx,funy,tinterval) plots over the specified interval. Specify the interval as a two-element vector of the form [tmin tmax].

fplot(___,LineSpec) specifies the line style, marker symbol, and line color. For example, '-r' plots a red line. Use this option after any of the input argument combinations in the previous syntaxes.

example

fplot(___,Name,Value) specifies line properties using one or more name-value pair arguments. For example, 'LineWidth',2 specifies a line width of 2 points.

fplot(ax,___) plots into the axes specified byax instead of the current axes (gca). Specify the axes as the first input argument.

example

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

[x,y] = fplot(___) returns the abscissas and ordinates for the function without creating a plot. This syntax will be removed in a future release. Use the XData and YData properties of the line object, fp, instead.

Note

fplot no longer supports input arguments for specifying the error tolerance or the number of evaluation points. To specify the number of evaluation points, use the MeshDensity property.

Examples

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Plot sin(x) over the default x interval [-5 5].

fplot(@(x) sin(x))

Plot the parametric curve and .

xt = @(t) cos(3*t);
yt = @(t) sin(2*t);
fplot(xt,yt)

Plot the piecewise function

Plot multiple lines using hold on. Specify the plotting intervals using the second input argument of fplot. Specify the color of the plotted lines as blue using 'b'. When you plot multiple lines in the same axes, the axis limits adjust to incorporate all the data.

fplot(@(x) exp(x),[-3 0],'b')
hold on
fplot(@(x) cos(x),[0 3],'b')
hold off
grid on

Plot three sine waves with different phases. For the first, use a line width of 2 points. For the second, specify a dashed red line style with circle markers. For the third, specify a cyan, dash-dotted line style with asterisk markers.

fplot(@(x) sin(x+pi/5),'Linewidth',2);
hold on
fplot(@(x) sin(x-pi/5),'--or');
fplot(@(x) sin(x),'-.*c')
hold off

Plot sin(x) and assign the function line object to a variable.

fp = fplot(@(x) sin(x))
fp = 
  FunctionLine with properties:

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

  Show all properties

Change the line to a dotted red line by using dot notation to set properties. Add cross markers and set the marker color to blue.

fp.LineStyle = ':';
fp.Color = 'r';
fp.Marker = 'x';
fp.MarkerEdgeColor = 'b';

Plot two lines using hold on.

fplot(@(x) sin(x))
hold on 
fplot(@(x) cos(x))
hold off

Plot from to using a function handle. Display the grid lines. Then, add a title and label the x-axis and y-axis.

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

Use gca to access the current axes object. Display tick marks along the x-axis at intervals of . Format the x-axis tick values by setting the XTick and XTickLabel properties of the axes object. Similar properties exist for the y-axis.

ax = gca;
ax.XTick = -2*pi:pi/2:2*pi;
ax.XTickLabel = {'-2\pi','-3\pi/2','-\pi','-\pi/2','0','\pi/2','\pi','3\pi/2','2\pi'};

Input Arguments

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Function to plot, specified as a function handle to a named or anonymous function.

Specify a function of the form y = f(x). The function 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).

Note

Support for character vector inputs will be removed in a future release. Use function handles instead.

Example: f = @(x) sin(x);

Interval for x, specified as a two-element vector of the form [xmin xmax].

Parametric function for x coordinates, specified as a function handle to a named or anonymous function.

Specify a function of the form x = funx(t). The function 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).

Example: funx = @(t) sin(2*t);

Parametric function for y coordinates, specified as a function handle to a named or anonymous function.

Specify a function of the form y = funy(t). The function 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).

Example: funy = @(t) cos(3*t);

Interval for t, specified as a two-element vector of the form [tmin tmax].

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

Line specification, specified as a character vector or string with a line style, marker, and color. The elements can appear in any order, and you can omit one or more options. To show only markers with no connecting lines, specify a marker and omit the line style.

Example: 'r--o' specifies a red color, a dashed line, and circle markers

Line Style SpecifierDescription
-Solid line (default)
--Dashed line
:Dotted line
-.Dash-dot line
Marker SpecifierDescription
oCircle
+Plus sign
*Asterisk
.Point
xCross
sSquare
dDiamond
^Upward-pointing triangle
vDownward-pointing triangle
>Right-pointing triangle
<Left-pointing triangle
pPentagram
hHexagram
Color SpecifierDescription

y

yellow

m

magenta

c

cyan

r

red

g

green

b

blue

w

white

k

black

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside single quotes (' '). You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

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

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

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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.

Line color, specified as an RGB triplet or one of the color options listed in the table.

For a custom color, specify an RGB triplet. 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]. Alternatively, you can specify some common colors by name. This table lists the long and short color name options and the equivalent RGB triplet values.

OptionDescriptionEquivalent RGB Triplet
'red' or 'r'Red[1 0 0]
'green' or 'g'Green[0 1 0]
'blue' or 'b'Blue[0 0 1]
'yellow' or 'y'Yellow[1 1 0]
'magenta' or 'm'Magenta[1 0 1]
'cyan' or 'c'Cyan[0 1 1]
'white' or 'w'White[1 1 1]
'black' or 'k'Black[0 0 0]

Example: 'blue'

Example: [0 0 1]

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

Line StyleDescriptionResulting Line
'-'Solid line

'--'Dashed line

':'Dotted line

'-.'Dash-dotted line

'none'No lineNo line

Line width, specified as a positive value in points. If the line has markers, then the line width also affects the marker edges.

Example: 0.75

Marker symbol, specified as one of the values in this table. By default, a line does not have markers. Add markers at selected points along the line by specifying a marker.

ValueDescription
'o'Circle
'+'Plus sign
'*'Asterisk
'.'Point
'x'Cross
'square' or 's'Square
'diamond' or 'd'Diamond
'^'Upward-pointing triangle
'v'Downward-pointing triangle
'>'Right-pointing triangle
'<'Left-pointing triangle
'pentagram' or 'p'Five-pointed star (pentagram)
'hexagram' or 'h'Six-pointed star (hexagram)
'none'No markers

Marker outline color, specified as 'auto', an RGB triplet, or one of the color options listed in the table. The default value of 'auto' uses the same color as the Color property.

For a custom color, specify an RGB triplet. 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]. Alternatively, you can specify some common colors by name. This table lists the long and short color name options and the equivalent RGB triplet values.

OptionDescriptionEquivalent RGB Triplet
'red' or 'r'Red[1 0 0]
'green' or 'g'Green[0 1 0]
'blue' or 'b'Blue[0 0 1]
'yellow' or 'y'Yellow[1 1 0]
'magenta' or 'm'Magenta[1 0 1]
'cyan' or 'c'Cyan[0 1 1]
'white' or 'w'White[1 1 1]
'black' or 'k'Black[0 0 0]
'none'No colorNot applicable

Example: [0.5 0.5 0.5]

Example: 'blue'

Marker fill color, specified as 'auto', an RGB triplet, or one of the color options listed in the table. The 'auto' value uses the same color as the MarkerEdgeColor property.

For a custom color, specify an RGB triplet. 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]. Alternatively, you can specify some common colors by name. This table lists the long and short color name options and the equivalent RGB triplet values.

OptionDescriptionEquivalent RGB Triplet
'red' or 'r'Red[1 0 0]
'green' or 'g'Green[0 1 0]
'blue' or 'b'Blue[0 0 1]
'yellow' or 'y'Yellow[1 1 0]
'magenta' or 'm'Magenta[1 0 1]
'cyan' or 'c'Cyan[0 1 1]
'white' or 'w'White[1 1 1]
'black' or 'k'Black[0 0 0]
'none'No colorNot applicable

Example: [0.3 0.2 0.1]

Example: 'green'

Marker size, specified as a positive value in points.

Example: 10

Output Arguments

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One or more FunctionLine or ParameterizedFunctionLine objects, returned as a scalar or a vector.

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

  • If you use the fplot(funx,funy) syntax or a variation of this syntax, then fplot returns ParameterizedFunctionLine 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

  • Use element-wise operators for the best performance and to avoid a warning message. For example, use x.*y instead of x*y. For more information, see Array vs. Matrix Operations.

  • When you zoom in on the chart, fplot replots the data, which can reveal hidden details.

Introduced before R2006a

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