MATLAB Function Reference |

**Syntax**

contour(Z) contour(Z,n) contour(Z,v) contour(X,Y,Z) contour(X,Y,Z,n) contour(X,Y,Z,v) contour(...,

) [C,h] = contour(...)*LineSpec*

**Description**

A contour plot displays isolines of matrix `Z`

. Label the contour lines using `clabel`

.

```
contour(Z)
```

draws a contour plot of matrix `Z`

, where `Z`

is interpreted as heights with respect to the *x*-*y* plane. `Z`

must be at least a 2-by-2 matrix. The number of contour levels and the values of the contour levels are chosen automatically based on the minimum and maximum values of `Z`

. The ranges of the *x*- and *y-*axis are `[1:n]`

and `[1:m]`

, where `[m,n] = size(Z)`

.

```
contour(Z,n)
```

draws a contour plot of matrix `Z`

with `n`

contour levels.

```
contour(Z,v)
```

draws a contour plot of matrix `Z`

with contour lines at the data values specified in vector `v`

. The number of contour levels is equal to `length(v)`

. To draw a single contour of level `i`

, use `contour(Z,[i i])`

.

```
contour(X,Y,Z), contour(X,Y,Z,n), and contour(X,Y,Z,v)
```

draw contour plots of `Z`

. `X`

and `Y `

specify the *x*- and *y*-axis limits. When `X`

and `Y`

are matrices, they must be the same size as `Z`

, in which case they specify a surface as `surf`

does.

```
contour(...,LineSpec)
```

draws the contours using the line type and color specified by `LineSpec`

. contour ignores marker symbols.

```
[C,h] = contour(...)
```

returns the contour matrix `C`

(see `contourc`

) and a vector of handles to graphics objects. `clabel`

uses the contour matrix `C`

to create the labels. `contour`

creates patch graphics objects unless you specify `LineSpec`

, in which case `contour`

creates line graphics objects.

**Remarks**

If you do not specify `LineSpec`

, `colormap`

and `caxis`

control the color.

If `X`

or `Y `

is irregularly spaced, `contour`

calculates contours using a regularly spaced contour grid, then transforms the data to `X`

or `Y`

.

**Examples**

To view a contour plot of the function

over the range -2 *x* 2, -2 *y* 3, create matrix `Z`

using the statements

Then, generate a contour plot of `Z`

.

View the same function over the same range with 20 evenly spaced contour lines and colored with the default colormap `jet`

.

Use `interp2`

to create smoother contours. Also set the contour label text `BackgroundColor`

to a light yellow and the `EdgeColor`

to light gray.

Z = magic(4); [C,h] = contour(interp2(Z,4)); h = clabel(C,h); set(h,'BackgroundColor',[1 1 .6],... 'Edgecolor',[.7 .7 .7])

**See Also**

`clabel`

, `contour3`

, `contourc`

, `contourf`

, `interp2`

, `quiver`

Contour Plots category for related functions

Contour Plots section for more examples

continue | contour3 |