scale

Scale geometry

Syntax

h = scale(g,s)

h = scale(g,s,refpoint)

Description

h = scale(g,s) scales the geometry g by the factor s with respect to the origin.

h = scale(g,s,refpoint) scales the geometry with respect to the reference point refpoint.

Examples

Scale 2-D Geometry

Scale a 2-D geometry along the x- and y-axis and ensure consistency with the mesh.

Create a model.

model = createpde;

Import and plot a geometry.

g = importGeometry(model,"PlateHolePlanar.stl");
pdegplot(model)

Mesh the geometry and plot the mesh.

generateMesh(model);

figure
pdemesh(model)

Scale the geometry by a factor of 10 along the x-axis.

scale(g,[10 1])

ans = 
  DiscreteGeometry with properties:

       NumCells: 0
       NumFaces: 1
       NumEdges: 5
    NumVertices: 5
       Vertices: [5×3 double]

Plot the geometry.

figure
pdegplot(model)

Plot the geometry and mesh. The scale function modifies a geometry, but it does not modify a mesh.

figure
pdegplot(model)
hold on
pdemesh(model)

After modifying the geometry, always regenerate the mesh.

generateMesh(model);

figure
pdegplot(model)
hold on
pdemesh(model)

Reflect the geometry across the x-axis and regenerate the mesh.

scale(g,[1 -1]);
generateMesh(model);

Plot the resulting geometry and mesh.

figure
subplot(2,1,1)
pdegplot(model)
subplot(2,1,2)
pdemesh(model)

Scale 3-D Geometry

Enlarge a geometry: first uniformly in all directions, and then using different scaling factors along different axes.

Create and plot a geometry.

g = multicuboid(1,1,1);
pdegplot(g,"VertexLabels","on","FaceAlpha",0.5)

Scale the geometry by a factor of 2 uniformly along all coordinate axes. Plot the result.

scale(g,2);
pdegplot(g,"VertexLabels","on","FaceAlpha",0.5)

Now scale by factors of 2, 3, and 4 along the x-, y-, and z-axes, respectively. Plot the result.

scale(g,[2 3 4]);
pdegplot(g,"VertexLabels","on","FaceAlpha",0.5)

Flip the geometry upside down by scaling it with the factor -1 and using the bottom front corner (vertex 1) as a reference point.

scale(g,[1 1 -1], [2 -3 0]);
pdegplot(g,"VertexLabels","on","FaceAlpha",0.5)

Input Arguments

g — Geometry

fegeometry object | DiscreteGeometry object | AnalyticGeometry object

Geometry, specified as an fegeometry object, a DiscreteGeometry object, or an AnalyticGeometry object.

s — Scaling factor

nonzero real number | vector of two or three nonzero real numbers

Scaling factor, specified as a real number or vector of two or three real numbers. Use one value for uniform scaling in all directions. Use a vector of two or three elements to specify different scaling factors along the x-, y-, and, for a 3-D geometry, z-axes.

refpoint — Reference point for scaling

vector of two or three real numbers

Reference point for scaling specified as a vector of two or three real numbers for a 2-D and 3-D geometry, respectively

Output Arguments

h — Resulting geometry

fegeometry object | handle

Resulting geometry, returned as an fegeometry object or a handle.

• If the original geometry g is an fegeometry object, then h is a new fegeometry object representing the modified geometry. The original geometry g remains unchanged.

• If the original geometry g is a DiscreteGeometry object, then h is a handle to the modified DiscreteGeometry object g.

• If g is an AnalyticGeometry object, then h is a handle to a new DiscreteGeometry object. The original geometry g remains unchanged.

Tips

• After modifying a geometry, regenerate the mesh to ensure a proper mesh association with the new geometry.

• If the scaling factor is negative, then the coordinates will flip their signs. The scaling factor of -1 mirrors the existing geometry if the reference point is the origin.

• If g is an fegeometry or AnalyticGeometry object, and you want to replace it with the modified geometry, assign the output to the original geometry, for example, g = scale(g,20).

Version History

Introduced in R2020a

R2023a: Finite element model

scale now accepts geometries specified by fegeometry objects.

R2021a: Geometry transformation for analytic geometries

scale now works with AnalyticGeometry objects.