Plotting with Matlab
All Matlab variables must have numerical values:
The basic plot command:
Note that the horizontal axis is marked according to the index, not the value of x. Fix this as follows:
This is the same thing as plotting "parametric curves."
|We can plot the "inverse relationship" (for example, the squaring function and +/- square root) easily:|
|>> plot( x, x.^2 )||>> plot( x.^2, x )|
|or a spiral in two or in three dimensions:|
|>> t = 0:.1:10; plot( t .* cos(t), t .* sin(t) )||>> plot3( t .* cos(t), t .* sin(t), t )|
Plot several curves simultaneously with plot(x1, y1, x2, y2, ...):
Let's add some options [first plot, then options] -- the order of the options can affect the result!
We will first make the scales [the "ratio"] equal, then set the plotting window to be -6 < x < 6, -2 < y < 2.
Here's another example, a semilog plot. In the graphic we also have introduced another variation, the "plot matrix" -- to learn more, enter the command help subplot
Here are other ways to graph multiple curves, using matrices (plotted by columns) and using "hold."
Functions of two variables may be plotted, as well, but some "setup" is required!
>> z = x.^2 - y.^2;
Here are two options for plotting the surface. Look at the help page for details.