[MUSIC]. We would have gotten the wrong answer,
but MATLAB wouldn't have known it. And it wouldn't have told us anything. Errors of semantics are the biggest
problem in computer science by far, because the rules that they violate are
unknown to the language we're using, so we get no help. Makes you kind of like
those red error messages. Well almost. MATLAB’s trying to help us with these
error messages of course, but there's a lot more help easily available in MATLAB. I
provides lots of commands like the who and whos commands that we use to look
at the variables in a work space. And the clear command that we used
earlier to remove all the variables from the workspace. All these commands are executed
by giving their names, and every one of them has something called
a help page, which is roughly a page, more or less, of explanations of the
syntax and the semantics of the command. We've seen that we can get information
about MATLAB's built-in functions by typing their names into
the search bar up here at the top. But there's a command that we can enter that
will print what we need to know right here in the command window. The name of the command is “help”. You just type help followed by the name
of the command you want to to know about. Let's do that to find out
about a command called “format”. [CLICKS] Here we see the so-called help page for
the command format, or I should say we see the bottom of the help
page, ‘cause it's a pretty long one, But we can scroll to the top by using the
scroll bar over at the right or the mouse wheel or your fingers on the
touch pad or however you like to do it. Every help page starts out by giving
the command name, in this case “format”, and telling you, in just
a few words, what the command does. So here we see: “Set output format.” This is followed by more detailed and
more detailed ways that you can use the command
and tells you what it does. You can read all about format later,
but right now let's scroll down until we find “format compact” and
“format loose”. Right here they are. You'll notice that COMPACT and LOOSE and these other options here are in upper
case just to make em easier to spot when you sweep over this
help page with your eyes. But you can use lower or
upper case for the command. Most people use lower case. Let's see what these two options do. First I'm going to set x equal to five. Now let's use format loose [CLICKS]. And, I'll repeat the command. [CLICKS]. Do you see the difference? By “loose”, MATLAB means that spaces
are inserted between the lines. I like a more compact output, myself. So I always change the setting
to compact like this. [CLICKS] Now we're back to normal, or what I call normal. [CLICKS] If your particular MATLAB
installation is set to loose, you may have been wondering
why you're getting these spaces and I'm not. Now you know. And you might want to go with compact. Another thing that the format command can
change for you is the number of decimal places that it shows when it prints
a response to an assignment statement. We can scroll up and see these options. Let's see here, if I can find them. There they are. I've got MATLAB set to SHORT, which says,
“Scaled fixed format to five digits.” Let's do another assignment statement. I'm going to do boy
equals 117 divided by 19. There are an infinite number
of digits in the exact answer. MATLAB shows five of them. 6.1579. Now let's try format long. [CLICKS] And I'll repeat that command. Let's use the up-arrow key to do that. Whoa!
This time, we've got lots of decimals. MATLAB is showing you all
the accuracy it's got. It's important to know,, though, that it works behind the scenes
with all the accuracy it's got, whether you have the format set to long or
short or anything else. All the command, format, affects is the printed output. You don't lose any accuracy
during the calculations when the format is set to short. You just don't see all
the accuracy in the output. I usually don't need to see all the
accuracy, so I tend to stick with short. And that's what I'm going to do. And there
we're back to five digits again. Let's see. Before I went off
on this format tangent, I was talking about the help command. And I wanted to tell you
some other things about it. For example, if you want to see the fancy
documentation with the fancy fonts that you get when you use
the search bar up here, you can also get that with
a command called “docs”. So let's try that with format. There, all this nice stuff shows up. It is pretty handy. We won't go into it, but we've seen
it before, and you can check it out. And here's another thing that we need to talk about. Suppose you don't know, you know, the name
of the command that you're looking for. You want to do plotting, for example, so
you could come up here and type plotting. And hit Return and, well, you see this
window, and you say, “Oh, this looks good.” You see Plotting Basics. Click that: How To Create 2-D Graph,
Add Title, Change the Limits. You know, “2-D graph”, that might be good. Create a line graph, 2-D. Oh, and here's some examples. It gives you a function. This is a workhorse function
right here called plot x y. We're going to look at that in
a minute. It shows you examples and so on. Now that you know plot is what you want you can type help plot, and scroll up here, and you'll see all kinds
of information about plot command. There is a linear plot and so on. There is one other thing you can do. Let's go down here and
look at this little thing. You've probably not noticed this before. This fx with this tiny down-arrow here. This is called “browse for functions”. Let's click on that. You see a little window show up
here with some stuff that says MATLAB, language fundamentals,
mathematics, graphics. I'm looking for plotting. That looks promising. Whoo, there you go! 2-D and 3-D Plots. I click there. Line Plots. And there is this plot
function that I mentioned, and here is some information
about it right here. So this is another way for you to find information about a function
when you don't even know its name. You just browse for it. Let me just bring up Chrome and type “How do I plot in matlab?” Well! 2-D line plot. That looks promising. Let’s see what we get there. And there we are.
That's exactly what we wanted. You'll usually get, not only the name of
the appropriate function like this, but you'll be taken right to
the help page that you need. MathWorks keeps all their documentation online so
it's available to everyone. And Google’s search engine is so magical that, well, I usually wonder why I didn't
just ask Google in the first place. [MUSIC] [APPLAUSE]
