- [Instructor] In the previous movie
I showed you how to create a script
to record a MATLAB procedure.
The main limitation of that script,
and it's an important one,
was that every value was written directly into the code.
There was no way to accept input.
In this movie I will show you how to accept
one or more input values for your MATLAB calculations.
I have run MATLAB and I'm looking
at a new blank command window.
I want to create a script so I will go to the home tab
and click the new script button.
I could also press control n.
And doing so displays a new editor window.
I've been working for a while so mine is called Untitled4.
Yours might have a different number.
I want my script to be able to accept input from a user.
So, I'll start by assigning a value to a variable.
I'll call that radius.
And my goal is to develop an equation
that calculates the volume of a sphere.
Rather than specifying the value directly,
I want to accept input,
and as you might imagine that uses the input keyword.
So I'll type input followed by a left parentheses
then a single quote because I'm providing a prompt
which is a string,
and I will ask Enter the radius of the sphere.
A stylistic note is that it's considered good practice
to add a colon after the input prompt.
That way the reader knows that you are in fact
asking for their input because the colon indicates
that it's not quite a full stop,
but it's expecting something more afterwards.
Right, then type a single quote,
and then a right parentheses,
and there you have your input.
And the red underlining indicating an error has gone away
so everything looks good.
Then enter and then the volume
should be set equal to four times pi
which is a built-in constant,
multiplied by the radius cubed,
so that would be a caret and a three divided by three.
So there is my formula.
Right, everything looks good,
so I will press control s to save,
and I will call it inputvolume
just to differentiate it from the sphere volume script
that we created elsewhere in the course.
Press enter and there I have my file.
I'll close it by going over to the editor window
and click the close editor button.
And then in the command window I will run my script
by typing in the name of the file
without the .m file extension.
So that is inputvolume and enter.
My input asks me to enter the radius of the sphere.
That's the prompt I created.
So I'll type in three and enter.
The radius equals three and volume equals 113.0973.
You can also accept multiple inputs,
basically through multiple input statements.
I'll create a new script so I will press control n.
So I get a new editor window
and my command window moves down.
And for this I will create a calculation
to calculate the area of a triangle,
which is one half of the base times the height.
So I'll press control s to save before I start
and I'll call it try area and enter.
So I'll have the
base equals = input('Enter the base of the triangle: ')
and everything looks good.
Enter.
Then the height so that'll be
height = input('Enter the height of the triangle: ')
and I'm getting an indication up here,
and I bet the program is wondering
if I want to actually display the base that was input.
So if I hover my mouse pointer over the one for height
it says terminate statement
with semicolon to suppress output.
Yeah, okay, so I'll put a semicolon after height
and a semicolon after the base line,
then I'll press enter.
And now I will type t_area to indicate triangle area.
And that is equal to one half, or 0.5
times the base times the height and enter.
And I definitely want to display that value.
So I'll press control s.
Everything looks good.
I'll close the triarea file
by clicking the close editor button.
And then in my command window
I will type the name of the file minus the .m extension.
So triarea enter.
Enter the base of the triangle.
Let's do 10 enter.
And the height will be six.
So if we're lucky the t_area will be 30,
one half the base times the height.
And there is our result.
Accepting input gives you a lot more flexibility
when you are working in MATLAB.
It also avoids the common programming error
of hardcoding values that really
should be put in by the user every time
they do the calculation.