Cant assign an input in a function with an elseif condition

Hi, I am trying to form a simple function which the user has to make two branching choice. The function receives an initial input of a time step size, and it should be used in both if scenarios. However, it only works for the first case but not the second. I attached the two .m files and this is the code:

function runselected()
%clear  I have deleted these two after the comments.
%clc
    time = input('Enter a time step value for the question which should be less than or equal to 10e-03 to overcome convergence problems: ')
    dt= time;
    choice = input('Enter 1 to run the solution for question a, 2 for b: ');
    if choice == 1 
        fprintf('Running for a: \n');
        run("hw4_a.m")
        T_FTCS
        T_CN
    elseif choice == 2
        time = input('Enter a time step value for the question (b) which should be less than or equal to 10e-03 to overcome convergence problems: ');
        dt= time;
        fprintf('Running for b: \n');
        run("hw4_b.m")
    else
        fprintf('Invalid choice. Enter either "1" or "2". \n');
    end
end
% This is the running function

%This is the error I get:

%Unrecognized function or variable 'dt'.

%Error in hw4_b (line 31)

% T_FTCS_new(i, j) = T_FTCS(i, j) + 1/alpha * dt * ((T_FTCS(i+1, j) - 2*T_FTCS(i, j) + T_FTCS(i-1, j)) / dx^2 + (T_FTCS(i, j+1) - 2*T_FTCS(i, j) + T_FTCS(i, j-1)) / dy^2);

%Error in run (line 91)

%evalin('caller', strcat(script, ';'));

%Error in runselected (line 20)

% run("hw4_b.m")

[Dyuman Joshi]

The line where dt is defined in the script hw4_b is commented out, thus the variable is not defined, which when used to define other variables gives the error.

Solution - Uncomment it.

Also, you don't need to use clear and clc under a function, so you can remove them.

[Metehan Kilic]

Yes, but that's the gist of it. Neither the hw4_a has a defined dt value, it is also commented out. I want to define it through the

time = input('Enter a time step value for the question which should be less than or equal to 10e-03 to overcome convergence problems: ')
dt= time;

lines. It works for the hw4_a but not the hw4_b, in otherwords the elseif command.

[Dyuman Joshi]

I'm not sure what's the anomaly here, but if you want to pass a value, define the files as functions.

I have changed the names of the function files, commented out input() calls, as they don't work here and converted choice as input to the main function just to show that both the choices work properly -

%choice = 1
runselected(1)

Running for a: 

%choice = 2
runselected(2)

Running for b: 
FTCS: Temperature at middle point is 15°C at t = 6.445 seconds.
Crank-Nicholson: Temperature at middle point is 15°C at t = 5.96 seconds.

%Main Function 
function runselected(choice)
    %input('Enter 1 to run the solution for question a, 2 for b: ');
    
    if choice == 1 
        dt = 0.005; %input('Enter a time step value for the question which should be less than or equal to 10e-03 to overcome convergence problems: ');
        fprintf('Running for a: \n');
        fun_hw4_a(dt)
    elseif choice == 2
        fprintf('Running for b: \n');
        dt = 0.005; %input('Enter a time step value for the question (b) which should be less than or equal to 10e-03 to overcome convergence problems: ');
        fun_hw4_b(dt)
    else
        fprintf('Invalid choice. Enter either "1" or "2". \n');
    end
end

[Stephen23]

Automatically writing CLEAR, CLOSE, CLC at the top of every piece of code:

https://www.baeldung.com/cs/anti-patterns

https://en.wikipedia.org/wiki/Anti-pattern

Answer 1

[Cris LaPierre]

Remove the clear statements in your code.

[Metehan Kilic]

I did, but still the same error pops up.

[Cris LaPierre]

Did you remove the clear that is at the top of your hw4_b.m script as well?

[Metehan Kilic]

Can't believe I missed it... Thanks.