# 2-D and 3-D Plots

### Line Plots

To create two-dimensional line plots, use the `plot`

function. For example, plot the sine function over a linearly spaced vector of values from 0 to $$2\pi $$:

x = linspace(0,2*pi); y = sin(x); plot(x,y)

You can label the axes and add a title.

xlabel("x") ylabel("sin(x)") title("Plot of the Sine Function")

By adding a third input argument to the `plot`

function, you can plot the same variables using a red dashed line.

`plot(x,y,"r--")`

`"r--"`

is a *line specification*. Each specification can include characters for the line color, style, and marker. A marker is a symbol that appears at each plotted data point, such as a `+`

, `o`

, or `*`

. For example, "`g:*"`

requests a dotted green line with `*`

markers.

Notice that the titles and labels that you defined for the first plot are no longer in the current figure window. By default, MATLAB® clears the figure each time you call a plotting function, resetting the axes and other elements to prepare the new plot.

To add plots to an existing figure, use `hold on`

. Until you use `hold off`

or close the window, all plots appear in the current figure window.

x = linspace(0,2*pi); y = sin(x); plot(x,y) hold on y2 = cos(x); plot(x,y2,":") legend("sin","cos") hold off

### 3-D Plots

Three-dimensional plots typically display a surface defined by a function in two variables, $$z=f(x,y)$$. For instance, calculate $$z=x{e}^{-{x}^{2}-{y}^{2}}$$ given row and column vectors `x`

and `y`

with 20 points each in the range [-2,2].

x = linspace(-2,2,20); y = x'; z = x .* exp(-x.^2 - y.^2);

Then, create a surface plot.

surf(x,y,z)

Both the `surf`

function and its companion `mesh`

display surfaces in three dimensions. `surf`

displays both the connecting lines and the faces of the surface in color. `mesh`

produces wireframe surfaces that color only the connecting lines.

### Multiple Plots

You can display multiple plots in different parts of the same window using either `tiledlayout`

or `subplot`

.

The `tiledlayout`

function was introduced in R2019b and provides more control over labels and spacing than `subplot`

. For example, create a 2-by-2 layout within a figure window. Then, call `nexttile`

each time you want a plot to appear in the next region.

t = tiledlayout(2,2); title(t,"Trigonometric Functions") x = linspace(0,30); nexttile plot(x,sin(x)) title("Sine") nexttile plot(x,cos(x)) title("Cosine") nexttile plot(x,tan(x)) title("Tangent") nexttile plot(x,sec(x)) title("Secant")

If you are using a release earlier than R2019b, see `subplot`

.