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fplot

Plot expression or function

Syntax

  • fplot(funx,funy)
    example
  • fplot(funx,funy,tinterval)
  • fplot(___,LineSpec)
  • fplot(___,Name,Value)
    example
  • fplot(ax,___)
  • fp = fplot(___)
    example
  • [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 function line object or a parameterized function line object, depending on the inputs. Use fp to query and modify properties of a specific line. For a list of properties, see Function Line Properties or Parameterized Function Line 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 function 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 $x = cos(3t)$ and $y = sin(2t)$.

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

Plot the piecewise function

$$ \matrix{e^x &amp; -3 < x < 0 \cr \cos(x) &amp; 0 < x < 3.}$$

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

  Use GET to 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 $\sin(x)$ from $-2\pi$ to $2\pi$ 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 $\pi/2$. 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 with a line style, marker, and color. The elements of the character vector 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 Function Line Properties or Parameterized Function Line 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 a character vector of a color name.

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]. This table lists the long and short color name options and the equivalent RGB triplet values.

Long NameShort NameRGB Triplet
'yellow''y'[1 1 0]
'magenta''m'[1 0 1]
'cyan''c'[0 1 1]
'red''r'[1 0 0]
'green''g'[0 1 0]
'blue''b'[0 0 1]
'white''w'[1 1 1]
'black''k'[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 one of these values:

  • 'auto' — Use the same color specified in the Color property.

  • 'none' — Use no color, which makes unfilled markers invisible.

  • RGB triplet or character vector of a color name — Use the specified color.

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]. This table lists the long and short color name options and the equivalent RGB triplet values.

Long NameShort NameRGB Triplet
'yellow''y'[1 1 0]
'magenta''m'[1 0 1]
'cyan''c'[0 1 1]
'red''r'[1 0 0]
'green''g'[0 1 0]
'blue''b'[0 0 1]
'white''w'[1 1 1]
'black''k'[0 0 0]

Example: [0.5 0.5 0.5]

Example: 'blue'

Marker fill color, specified as one of these values:

  • 'none' — Use no color, which makes the interior invisible.

  • 'auto' — Use the same color specified in the MarkerEdgeColor property.

  • RGB triplet or character vector of a color name — Use the specified color.

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]. This table lists the long and short color name options and the equivalent RGB triplet values.

Long NameShort NameRGB Triplet
'yellow''y'[1 1 0]
'magenta''m'[1 0 1]
'cyan''c'[0 1 1]
'red''r'[1 0 0]
'green''g'[0 1 0]
'blue''b'[0 0 1]
'white''w'[1 1 1]
'black''k'[0 0 0]

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 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(funx,funy) 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 Function Line Properties and Parameterized Function Line Properties.

More About

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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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