# pdecont

Contour plot of PDE node or triangle data

This page describes the legacy workflow. Use it when you work with legacy code and do not plan to convert it to use the recommended approach. Otherwise, use `pdeplot`.

## Syntax

``pdecont(p,t,u)``
``pdecont(p,t,u,n)``
``pdecont(p,t,u,v)``
``h = pdecont(___)``

## Description

example

````pdecont(p,t,u)` creates a contour plot of node data or triangle data. By default, `pdecont` uses 10 levels for a contour plot. The `p` and `t` arguments specify the geometry of the PDE problem.If `u` is a column vector, `pdecont` treats it as a node data. If `u` is a row vector, `pdesurf` treats it as a triangle data.```

example

````pdecont(p,t,u,n)` plots `n` levels.```

example

````pdecont(p,t,u,v)` plots levels at the solution heights specified by `v`.```
````h = pdecont(___)` uses any of the previous syntaxes and returns handles to the drawn axes objects.```

## Examples

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Plot contours of the solution to the equation $-\Delta u=1$ on the L-shaped membrane using the `pdecont` function.

First, create and refine a `[p,e,t]` mesh on the L-shaped membrane.

```[p,e,t] = initmesh('lshapeg'); [p,e,t] = refinemesh('lshapeg',p,e,t);```

Solve the equation using the Dirichlet boundary conditions $u=0$ on $\partial \Omega$.

`u = assempde('lshapeb',p,e,t,1,0,1);`

Plot the solution using the `pdesurf` function.

`pdesurf(p,t,u)` Plot contours of the solution using the `pdecont` function. By default, there are 10 levels.

`pdecont(p,t,u)` Now plot the contours using three levels.

`pdecont(p,t,u,3)` Plot the contours of the solution at the heights 0, 0.05, 0.1, and 0.14.

`pdecont(p,t,u,[0 0.05 0.1 0.14])` ## Input Arguments

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Mesh points, specified as a 2-by-`Np` matrix of points, where `Np` is the number of points in the mesh. For details on the mesh data representation, see `initmesh`.

Data Types: `double`

Mesh triangles, specified as a `4`-by-`Nt` matrix of triangles, where `Nt` is the number of triangles in the mesh. For details on the mesh data representation, see `initmesh`.

Data Types: `double`

PDE solution, specified as a vector.

The `pdesurf` function treats a column vector as node data and uses continuous style and interpolated shading. The function treats a row vector as triangle data and uses discontinuous style and flat shading.

Data Types: `double`

Number of levels, specified as a positive integer.

Data Types: `double`

Levels to plot, specified as a vector of heights.

Data Types: `double`

## Output Arguments

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Handles to graphics objects, returned as a vector.

## Tips 