#
3D Contour Plots
in
MATLAB^{®}

How to make 3D Contour Plots in MATLAB^{®} with Plotly.

## Contours of Sphere

Define `Z`

as a function of `X`

and `Y`

. In this case, call the `sphere`

function to create `X`

, `Y`

, and `Z`

. Then plot the contours of `Z`

.

```
[X,Y,Z] = sphere(50);
contour3(X,Y,Z);
fig2plotly(gcf, 'TreatAs', 'contour3');
```

## Contours at Fifty Levels

Define `Z`

as a function of two variables, `X`

and `Y`

. Then plot the contours of `Z`

. In this case, let MATLAB® choose the contours and the limits for the x- and y-axes.

```
[X,Y] = meshgrid(-5:0.25:5);
Z = X.^2 + Y.^2;
contour3(Z)
fig2plotly(gcf, 'TreatAs', 'contour3');
```

Now specify `50`

contour levels, and display the results within the x and y limits used to calculate `Z`

.

```
[X,Y] = meshgrid(-5:0.25:5);
Z = X.^2 + Y.^2;
contour3(X,Y,Z,50)
fig2plotly(gcf, 'TreatAs', 'contour3');
```

## Contours at Specific Levels with Labels

Define `Z`

as a function of two variables, `X`

and `Y`

. Then plot the contours at `Z = [-.2 -.1 .1 .2]`

. Show the contour labels by setting the `ShowText`

property to `'on'`

.

```
[X,Y] = meshgrid(-2:0.25:2);
Z = X.*exp(-X.^2-Y.^2);
contour3(X,Y,Z,[-.2 -.1 .1 .2],'ShowText','on')
fig2plotly(gcf, 'TreatAs', 'contour3');
```

## Contours at One Level

Define `Z`

as a function of `X`

and `Y`

. In this case, call the `peaks`

function to create `X`

, `Y`

, and `Z`

. Then display the contours at `Z = 2`

.

```
[X,Y,Z] = peaks;
contour3(X,Y,Z,[2 2]);
fig2plotly(gcf, 'TreatAs', 'contour3');
```

## Custom Line Width

Define `Z`

as a function of two variables, `X`

and `Y`

. Plot 30 contours of `Z`

, and then set the line width to `3`

.

```
[X,Y] = meshgrid(-2:0.0125:2);
Z = X.*exp(-X.^2-Y.^2);
[M,c] = contour3(X,Y,Z,30);
c.LineWidth = 3;
fig2plotly(gcf, 'TreatAs', 'contour3');
```