Can't call my function to another m file

I have two m files containing in one folder. I want to calculate error of exact and numerical solution on the third m file. The functions names are

T_exact=ExactSol(x,t,alpha,y);
T_num=NumericalSol(x,nj,r,t_end);

The code to the third file is given below:

alpha=10^-3;
T1=800;
T2=200;
nj=100;
T0=T1*ones(nj,1);
T0(nj/2+1:nj)=T2*ones(1,nj/2);
r=0.4;
t_end=50;
delta_x=1/nj;
x=([1+nj]-0.5)/nj;
T_num=NumericalSol(x,nj,r,t_end);
T_exact=ExactSol(x,t,alpha,y)
err=sqrt(delta_x*(T_num-T_exact)*(T_num-T_exact))

The Names of two m files are Assigment_2 and Assigment_1. I am recieving an error that T_num and T_exact are't defined. How to solve this problem?

[Rik]

Where did you store the NumericalSol and ExactSol functions?

[Muhammad Umar Khan]

How to store them?

[Rik]

You didn't write the function on a piece of paper. In which file did you store the function? And where is that file located relative to you current folder?

The code Bjorn suggested ( which('ExactSol') ) should answer most of that question.

[Muhammad Umar Khan]

All are in same folder File path is c:desktop/matlab

I can track Assignment_1 but can't track function

[Rik]

So those two functions are in Assignment_1.m?

I would suggest you go back to the previous lessons of your Matlab course to have a look again at the fundamentals. Another option is to do the Onramp course that is provided by Mathworks for free.

[Muhammad Umar Khan]

Taxact in Assignment_1 and T_NumericalSol in Assignment_2

[Rik]

Please attach these two files to your question. You're treating them as functions in the code you posted, but it is unclear if you made them actual functions.

Answer 1

[Bjorn Gustavsson]

If you have your third m-file in another directory and the first directory is not on the matlab-path then matlab will not know about their existence. You can check this with

which ExactSol

If that doesn't return with the full path to your function then you have to add that first directory to you path. I typically do that something like this:

addpath /home/bjorn/matlab/first_directory_name -end

where you can make the suitable replacements. I use -end just to make sure that I dont by accident shadow any of matlab's functions with any of my functions - this is unusual but then will break some matlab-functionality.

Also check the documentation for path.

HTH

[Muhammad Umar Khan]

I have done all this but it still shows the same error

[Bjorn Gustavsson]

So what does

which ExactSol

return?

[Muhammad Umar Khan]

Can't find ExactSol

[Bjorn Gustavsson]

OK, do this (with suitable changes to your folder names):

• save the ExactSol-function in a file ExactSol.m and the function _ NumericalSol_ in a file NumericalSol.m

• Make sure that you have the directory where you save these functions on the matlab-path, as outlined above.

HTH

[Steven Lord]

I agree with Bjorn. If the name of a function in a function file does not match the name of the function file itself, MATLAB will identify the function using the file name not the function name. [See the first Note on this documentation page.] If the following code was in a file named banana.m

function y = watermelon(x)
y = 2*x;
end

you would call this function as

y = banana(1:10)

not as

y = watermelon(1:10)

[Muhammad Umar Khan]

Thank you I got

[Bjorn Gustavsson]

@Steven, and everyone - even if it worked to call functions "by-name-hidden-in-files-with-other-names" it would be a nightmare trying to remember what files to edit and maintain.