pdegplot

Plot PDE geometry

Syntax

pdegplot(g)

pdegplot(g,Name,Value)

h = pdegplot(___)

Description

pdegplot(g) plots the geometry of a PDE problem, as described in g.

pdegplot(g,Name,Value) plots with additional options specified by one or more name-value arguments. For example, you can specify whether to display vertex, edge, face, and cell labels.

h = pdegplot(___) returns handles to the graphics, using any of the previous syntaxes.

Examples

Plot 2-D Geometry

Plot the geometry of a region defined by a few simple shapes.

g = [2	 1      1     1      1     1      1     1     1     4     4;
    -1	-0.6   -0.5  -0.4   -0.5   0.4	  0.5	0.6   0.5  -1	  0.17;
     1	-0.5   -0.4  -0.5   -0.6   0.5    0.6   0.5   0.4   0.17  1;
     0	-0.25  -0.35 -0.25  -0.15 -0.25  -0.35 -0.25 -0.15  0    -0.74;
     0	-0.35  -0.25 -0.15  -0.25 -0.35	 -0.25 -0.15 -0.25 -0.74  0;
     0	 0      0     0      0     0      0     0     0     1     1;
     1	 1      1     1      1     1      1     1     1     0     0;
     0  -0.5   -0.5  -0.5   -0.5   0.5    0.5   0.5   0.5   0     0;
     0  -0.25  -0.25 -0.25  -0.25 -0.25  -0.25 -0.25 -0.25  0     0;
     0	 0.1    0.1   0.1    0.1   0.1    0.1   0.1   0.1   1     1;
     0	 0      0     0      0     0      0     0     0     0.75  0.75;
     0	 0      0     0      0     0      0     0     0     0     0];
 pdegplot(g)

View the vertex labels, edge labels, and the face label. Add space at the top of the plot to see the top edge clearly.

pdegplot(g,VertexLabels="on", ...
           EdgeLabels="on", ...
           FaceLabels="on")
ylim([-.8,.1])

Plot 3-D Geometry

Import a 3-D geometry file. Plot the geometry and turn on face labels. To see the labels on all faces of the geometry, set the transparency to 0.5.

gm = fegeometry("BracketWithHole.stl");
pdegplot(gm,FaceLabels="on",FaceAlpha=0.5)

Plot Multi-Cellular 3-D Geometry

Import a 3-D geometry file. Plot the geometry and turn on cell labels.

gm = fegeometry("DampingMounts.stl");
pdegplot(gm,CellLabels="on")

Lighting Effects on 3-D Plots

Since R2023b

Create and plot a 3-D geometry consisting of three nested cuboids of the same height. By default, pdegplot uses lighting effects to display geometric features, like different cells, with more contrast.

gm = multicuboid([2 3 5],[4 6 10],3);
pdegplot(gm,CellLabels="on",FaceAlpha=0.3)

To obtain the same plot appearance as in R2023a or earlier, turn off the lighting effects.

figure
pdegplot(gm,CellLabels="on",FaceAlpha=0.3,Lighting="off")

Specify Face Color

Since R2025a

Create a plot showing a watercolor paint set with two rows, each containing three pans of paint. First, create the geometry representing the container for the paint set.

L = 0.6;
W = 0.4;
H = 0.05;
g = multicuboid(W,L,H);
g = fegeometry(translate(g,[0,L/2,0]));

Create the geometry representing an individual pan of paint.

gPan = fegeometry(multicylinder(W/6,H/2));

Create a vector containing the colors you want to use for the six pans of paint. For example, specify these colors.

color = ["red","green","blue","yellow","magenta","black"];

Specify the gap from the edge of the container to the first pan.

edgeGap = 0.1;

Plot the container and specify white as the face color. Use the vector color to specify the face colors for the pans of paint.

pdegplot(g,FaceColor="white")
hold on
i = 1;
for k=linspace(edgeGap,L-edgeGap,3) % 3 pans in a row
    gColor = translate(gPan,[edgeGap,k,1.01*H/2]);
    pdegplot(gColor,FaceColor=color(i)) 
    hold on
    i = i + 1;
    % Mirror the geometry to create a pan in the second row.
    gColor = scale(gColor,[-1 1 1]);
    pdegplot(gColor,FaceColor=color(i))
    hold on
    i = i + 1;
end

Input Arguments

g — Geometry description

femodel object | fegeometry object | PDEModel object | DiscreteGeometry object | AnalyticGeometry object | output of decsg | decomposed geometry matrix | name of geometry file | function handle to geometry file

Geometry description, specified by one of these values:

• femodel object

• fegeometry object

• PDEModel object

• DiscreteGeometry object

• AnalyticGeometry object

• Output of decsg

• Decomposed geometry matrix (see Decomposed Geometry Data Structure)

• Name of geometry file (see Parameterized Function for 2-D Geometry Creation)

• Function handle to geometry file (see Parameterized Function for 2-D Geometry Creation)

Data Types: double | char | string | function_handle

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: pdegplot(g,FaceLabels="on")

Example: pdegplot(g,FaceColor=[0 0 1])

VertexLabels — Vertex labels for 2-D or 3-D geometry

"off" (default) | "on"

Vertex labels for 2-D or 3-D geometry, specified as "off" or "on".

Data Types: char | string

EdgeLabels — Boundary edge labels for 2-D or 3-D geometry

"off" (default) | "on"

Boundary edge labels for 2-D or 3-D geometry, specified as "off" or "on".

Data Types: char | string

FaceLabels — Boundary face labels for 2-D or 3-D geometry

"off" (default) | "on"

Boundary face labels for 2-D or 3-D geometry, specified as "off" or "on".

Data Types: char | string

CellLabels — Cell labels for 3-D geometry

"off" (default) | "on"

Cell labels for 3-D geometry, specified as "off" or "on".

Data Types: char | string

FaceAlpha — Surface transparency for 3-D geometry

1 (default) | real number from 0 through 1

Surface transparency for 3-D geometry, specified as a real number from 0 through 1. The default value 1 indicates no transparency. The value 0 indicates complete transparency.

Example: FaceAlpha=0.5

Data Types: double

FaceColor — Face color

[0.85 0.85 0.85] (default) | color name | RGB triplet | "none"

Since R2025a

Face color, specified as a color name, an RGB triplet, or "none". The specified color applies to all faces of the geometry. You cannot specify colors for individual faces.

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. For details on acceptable face colors, see FaceColor.

Long Name	Short Name	RGB 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]

Data Types: double | char | string

Lighting — Lighting effects for 3-D geometry

"on" (default) | "off"

Since R2023b

Lighting effects for 3-D geometry, specified as "on" or "off".

Data Types: char | string

Output Arguments

h — Handles to graphics objects

vector

Handles to graphics objects, returned as a vector.

Alternative Functionality

App

If you create a 2-D geometry in the PDE Modeler app, you can view the geometry from Boundary Mode. To see the edge labels, select Boundary > Show Edge Labels. To see the face labels, select PDE > Show Subdomain Labels.

Version History

Introduced before R2006a

R2025a: Specify the geometry face color

Specify the color for geometry faces by using the FaceColor argument. The specified color applies to all faces of the geometry. You cannot specify colors for individual faces.

R2023b: Control lighting effects

pdegplot now uses lighting effects by default to display geometric features with more contrast. To obtain the same plot appearance as in the previous releases, you can turn off lighting effects by setting the Lighting name-value argument to "off".

R2023a: Finite element geometry support

pdegplot now plots geometries specified by fegeometry and femodel objects.

R2020a: Improved performance for plots with many text labels

pdegplot shows faster rendering and better responsiveness for plots that display many text labels. Code containing findobj(fig,'Type','Text') no longer returns labels on figures produced by pdegplot.

R2016b: Specify transparency, and display vertex and cell labels

You can now set plot transparency by using FaceAlpha, and display vertex and cell labels by using VertexLabels and CellLabels, respectively.

The argument SubdomainLabels is no longer recommended. Use FaceLabels for 2-D geometries instead.

R2012b: Display edge and subdomain labels

Display edge and subdomain labels by setting EdgeLabels or SubdomainLabels to 'on'.