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.
'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
*. For example,
'g:*' requests a dotted green line with
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
[X,Y] = meshgrid(-2:.2:2); Z = X .* exp(-X.^2 - Y.^2);
Then, create a surface plot.
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
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');