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

function. For example, plot the value of the sine function from 0 to :

x = 0:pi/100:2*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 = 0:pi/100:2*pi; y = sin(x); plot(x,y) hold on y2 = cos(x); plot(x,y2,':') legend('sin','cos') hold off

Three-dimensional plots typically display a surface defined by a function in two variables, *z = f(x,y)* .

To evaluate *z*, first create a set of (*x,y*) points over the domain of the function using `meshgrid`

.

[X,Y] = meshgrid(-2:.2:2); 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 lines connecting the defining points.

You can display multiple plots in different subregions of the same window using the `subplot`

function.

The first two inputs to `subplot`

indicate the number of plots in each row and column. The third input specifies which plot is active. For example, create four plots in a 2-by-2 grid within a figure window.

t = 0:pi/10:2*pi; [X,Y,Z] = cylinder(4*cos(t)); subplot(2,2,1); mesh(X); title('X'); subplot(2,2,2); mesh(Y); title('Y'); subplot(2,2,3); mesh(Z); title('Z'); subplot(2,2,4); mesh(X,Y,Z); title('X,Y,Z');

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