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fplot

Plot expression or function

fplot no longer supports specifying the error tolerance, the number of evaluation points, or the y-axis limits using input arguments. Support for the [x,y] = fplot(_) syntax and character vector inputs will be removed in a future release. For more information, see Function Plots in the graphics release notes.

Syntax

  • fplot(xt,yt)
    example
  • fplot(xt,yt,tinterval)
  • fplot(___,LineSpec)
  • fplot(___,Name,Value)
    example
  • fplot(ax,___)
  • fp = fplot(___)
    example
  • [x,y] = fplot(___)

Description

example

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

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

fplot(___,LineSpec) sets the line style, marker symbol, and line color. 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. Name,Value pair settings apply to all the lines plotted.

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

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.

Examples

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Plot Expression

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

fplot(@(x) sin(x))

Plot Parametric Curve

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

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

Specify Plotting Interval and Plot Piecewise Functions

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

Specify Line Properties and Display Markers

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

Modify Line Properties After Creation

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 Multiple Lines in Same Axes

Plot two lines using hold on.

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

Add Title and Axis Labels and Format Ticks

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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f — Expression or function to plotanonymous function | function handle

Expression or function to plot, specified as an anonymous function or a function handle.

    Note:   Support for character vector inputs will be removed in a future release. Use an anonymous function or a function handle instead.

xinterval — Interval for x[–5 5] (default) | two-element vector of form [xmin xmax]

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

xt — Parametric function for x coordinatesanonymous function | function handle

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

yt — Parametric function for y coordinatesanonymous function | function handle

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

tinterval — Interval for t[–5 5] (default) | two-element vector of form [tmin tmax]

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

ax — Axes objectaxes object

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

LineSpec — Line specificationcharacter vector

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.

'MeshDensity' — Number of evaluation points23 (default) | number

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.

'Color' — Line color[0 0.4470 0.7410] (default) | RGB triplet | character vector

Line color, specified as an RGB triplet, a character vector of a color name, or 'none'. If you specify the Color as 'none', then the line is invisible.

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]

'LineStyle' — Line style'-' (default) | '--' | ':' | '-.' | 'none'

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

ValueDescriptionResult
'-'Solid line

'--'Dashed line

':'Dotted line

'-.'Dash-dotted line

'none'No lineNo line

'LineWidth' — Line width0.5 (default) | positive value

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' — Marker symbol'none' (default) | 'o' | '+' | '*' | '.' | 'x' | 's' | 'd' | ...

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

'MarkerEdgeColor' — Marker outline color'auto' (default) | 'none' | RGB triplet | character vector

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'

'MarkerFaceColor' — Marker fill color'none' (default) | 'auto' | RGB triplet | character vector

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'

'MarkerSize' — Marker size6 (default) | positive value

Marker size, specified as a positive value in points.

Example: 10

Output Arguments

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fp — One or more function or parameterized function line objectsscalar | vector

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.

These objects are unique identifiers, which you can use 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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