fimplicit

Plot implicit function

Syntax

fimplicit(f)

fimplicit(f,interval)

fimplicit(ax,___)

fimplicit(___,LineSpec)

fimplicit(___,Name,Value)

fp = fimplicit(___)

Description

fimplicit(f) plots the implicit function defined by f(x,y) = 0 over the default interval [-5 5] for x and y.

fimplicit(f,interval) specifies the plotting interval for x and y.

fimplicit(ax,___) plots into the axes specified by ax instead of into the current axes. Specify the axes as the first input argument, prior to any of the previous input arguments.

fimplicit(___,LineSpec) specifies the line style, marker symbol, and line color. For example, '-r' plots a red line.

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

fp = fimplicit(___) returns the ImplicitFunctionLine object. Use fp to access and modify properties of the line after it is created. For a list of properties, see ImplicitFunctionLine Properties.

Examples

Plot Implicit Function

Plot the hyperbola described by the function over the default interval of [-5 5] for x and y.

fimplicit(@(x,y) x.^2 - y.^2 - 1)

Specify Plotting Interval

Plot the function over the intervals [-3 0] for x and [-2 2] for y.

f = @(x,y) x.^2 + y.^2 - 3;
fimplicit(f,[-3 0 -2 2])

Modify Appearance of Implicit Plot

Plot two circles centered at (0,0) with different radius values. For the first circle, use a dotted, red line. For the second circle, use a dashed, green line with a line width of 2 points.

f1 = @(x,y) x.^2 + y.^2 - 1;
fimplicit(f1,':r')

hold on
f2 = @(x,y) x.^2 + y.^2 - 2;
fimplicit(f2,'--g','LineWidth',2)
hold off

Modify Implicit Plot After Creation

Plot the implicit function and assign the implicit function line object to the variable fp.

fp = fimplicit(@(x,y) y.*sin(x) + x.*cos(y) - 1)

fp = 
  ImplicitFunctionLine with properties:

     Function: @(x,y)y.*sin(x)+x.*cos(y)-1
        Color: [0 0.4470 0.7410]
    LineStyle: '-'
    LineWidth: 0.5000

  Show all properties

Use fp to access and modify properties of the implicit function line object after it is created. For example, change the color, line style, and line width.

fp.Color = 'r';
fp.LineStyle = '--';
fp.LineWidth = 2;

Input Arguments

f — Implicit function to plot

function handle

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

Specify a function of the form z = f(x,y). The function must accept two matrix input arguments and return a matrix 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: fimplicit(@(x,y) x.^2 - y.^2 + 1)

interval — Plotting interval for x and y

[-5 5] (default) | two-element vector | four-element vector

Plotting interval for x and y, specified in one of these forms:

• Two-element vector of the form [min max] — Use the same plotting interval of [min max] for both x and y.

• Four-element vector of the form [xmin xmax ymin ymax] — Use different plotting intervals for x and y. Plot over the interval [xmin xmax] for x and [ymin ymax] for y.

Example: fimplicit(f,[-2 3 -5 0])

LineSpec — Line style, marker symbol, and color

character vector | string

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

Example: fimplicit(f,'--or') plots a red, dashed line with circle markers.

Line Style	Description
-	Solid line (default)
--	Dashed line
:	Dotted line
-.	Dash-dot line

Marker	Description
o	Circle
+	Plus sign
*	Asterisk
.	Point
x	Cross
s	Square
d	Diamond
^	Upward-pointing triangle
v	Downward-pointing triangle
>	Right-pointing triangle
<	Left-pointing triangle
p	Pentagram
h	Hexagram

Color	Description
y	yellow
m	magenta
c	cyan
r	red
g	green
b	blue
w	white
k	black

ax — Axes object

axes object

Axes object. If you do not specify the axes, then fimplicit uses the current axes.

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: fimplicit(f,'MeshDensity',50,'LineWidth',2) specifies the number of evaluation points and the line width.

The ImplicitFunctionLine properties listed here are only a subset. For a complete list, see ImplicitFunctionLine Properties.

'MeshDensity' — Number of evaluation points per direction

151 (default) | scalar

Number of evaluation points per direction, specified as a scalar.

'Color' — Line color

[0 0 1] (default) | RGB triplet | 'r' | 'g' | 'b' | ...

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.

Option	Description	Equivalent 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 color	Not applicable

Example: 'blue'

Example: [0 0 1]

'LineStyle' — Line style

'-' (default) | '--' | ':' | '-.' | 'none'

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

Line Style	Description	Resulting Line
'-'	Solid line
'--'	Dashed line
':'	Dotted line
'-.'	Dash-dotted line
'none'	No line	No line

'LineWidth' — Line width

0.5 (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' | ...

Marker symbol, specified as one of the markers listed in this table. By default, the line does not have markers. Specifying a marker symbol adds markers at selected points along the line.

Value	Description
'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

Example: '+'

Example: 'diamond'

'MarkerSize' — Marker size

6 (default) | positive value

Marker size, specified as a positive value in points.

Example: 10

'MarkerEdgeColor' — Marker outline color

'auto' (default) | RGB triplet | 'r' | 'g' | 'b' | ...

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.

Option	Description	Equivalent 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 color	Not applicable

Example: [0.5 0.5 0.5]

Example: 'blue'

'MarkerFaceColor' — Marker fill color

'none' (default) | 'auto' | RGB triplet | 'r' | 'g' | 'b' | ...

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.

Option	Description	Equivalent 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 color	Not applicable

Example: [0.3 0.2 0.1]

Example: 'green'

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, fimplicit recalculates the data, which can reveal hidden details.