error using function code

I have an assignment due soon and i can not get matlab to work. I have never used matlab before and this is my first asignment in it. I have to make a program where i input a score fom 0 to 100 and it tells me what the grade is.

the first line of code needs to be

function grade = lettergrade(score)

but every time i try this, i get a error and matlab will not let me proced. I have even tried to copy someones code and it fails. I even copied the example from my book by copy paste and it throws the same error

error: function definition not supported in this context. functions can only be created as local or nested functions

no idea what the heck this even means

[Matt Thomas]

Answer 1

[James Tursa]

Create a file called lettergrade.m somewhere on the MATLAB path (e.g., in your working directory)

edit lettergrade.m

Copy all of your lettergrade function code into that file and save it.

Then simply call the lettergrade function like you would call any other function. From the command line or from within another file.

The reason what you are currently doing isn't working is because MATLAB thinks you are trying to create a function on the fly at the command line.

Note that if you were trying to create a function called "grade" as your example code shows, you would create a file called grade.m rather than lettergrade.m (but your instructions are to create a function called lettergrade)

[Matt Thomas]

how do i create an m file and save it? i have no idea how to use matlab haha

[James Tursa]

I showed you exactly what to type to create the file. Simply type this at the command line:

edit lettergrade.m

You can copy and paste text code into the file using the usual Ctrl-c and Ctrl-v stuff. To save it simply click on the "disk" icon as you would in any other application.

[Matt Thomas]

ohhh, i didnt know the "edit lettergrade.m" created the m file. I thought it edited the m file i needed to create first haha.

ok, i will try this. thanks

[James Tursa]

It does both. If the file already exists then it will edit the file. If the file doesn't exist then it will create it.

Answer 2

[Voss]

This error means you cannot define a function on the MATLAB command-line. You need to create an m-file and define the function in there.

For example, if your function should be called lettergrade, you can enter

edit lettergrade

on the command-line (and say yes if MATLAB asks you if you want to create a new m-file).

Then put the code in there, with the first line being:

function grade = lettergrade(score)

After that's done, then you can run the function from the command-line or from other functions (or from scripts, which are also m-files) by doing, say,

my_grade = lettergrade(84);

which should store the value 'B' in the variable my_grade, since an 84 should be a B.

[Matt Thomas]

ok, that makes sense now. i have never programmed or used matlab and this class is brutal haha.

thanks for the help

[Steven Lord]

Since you've never used MATLAB before I suggest you start with the free 2 hour MATLAB Onramp tutorial (https://www.mathworks.com/support/learn-with-matlab-tutorials.html) to quickly learn the essentials of MATLAB.

[Matt Thomas]

i can do that. thanks for showing me that. Does it cover things like if, elseif, for loops etc?

[Cris LaPierre]

See this page on creating functions in file:

• https://www.mathworks.com/help/matlab/matlab_prog/create-functions-in-files.html

Ch 12 of MATLAB Onramp coversthe basics of if statements and for loops.