Create mfile for a loop function

I was wondering if it is possible to create a function in mfile format for the bellow code (b0_T03_s is a table):

% to find x velocity and x position for bike #0

for i= 0:1:23;

b0_T03_s(2+i,25) = b0_T03_s(1+i,25) + b0_T03_s(1+i,23);

b0_T03_s(2+i,24) = b0_T03_s(1+i,24) + b0_T03_s(1+i,25) + (0.5*b0_T03_s(1+i,23));

end

[Abderrahim. B]

HI!

Do you mean to convert this snap of code into a MATLAB function?

[Reem RA]

yes exactly

Answer 1

[Cris LaPierre]

Yes, it's possible. See this page on creating live functions in a live script using the Refactor tool.

The orginal and refactored code must be live scripts (.mlx file type) to use this tool, but once created, you can save as *.m if necessary.

[Reem RA]

Thanks a lot, I will check the page that you have shared.

[Reem RA]

Can you explain why am I keep getting this error:

"the variable b0_T03_s appears to change size on every loop iteration, consider preallocating for speed"

Is this because I am using an array in the function?

[Cris LaPierre]

No, it's because you are creating an array inside your for loop.

b0_T03_s(2+i,25)

The suggestion to preallocate means to create your variable of the desired final size first using dummy values (0s, 1s, nans, etc).

b0_T03_s = zeros(25);
for ...

You many need to adjust this code depending on if b0_T03_s has some values you want to keep, but this is the idea. In the end, what you are seeing is just a warning, not an error, so you can also just ignore it.

[Reem RA]

Thanks a lot for your reply, appreciate it.

I am still getting the same error, in my case for the loop to start, I have to assign inital values for the first row, can you suggest an idea or refer some explanation to re-write this code?

function xf
b0_T03_sCopy(1,24) = b0_T03_sCopy(1,6);
b0_T03_sCopy(1,25) = b0_T03_sCopy(1,11);
for i= 0:1:23
b0_T03_sCopy(2+i,25) = b0_T03_sCopy(1+i,25) + b0_T03_sCopy(1+i,23);
b0_T03_sCopy(2+i,24) = b0_T03_sCopy(1+i,24) + b0_T03_sCopy(1+i,25) + (0.5*b0_T03_sCopy(1+i,23));
end

[Cris LaPierre]

I suggest taking a look at this page: https://www.mathworks.com/help/matlab/matlab_prog/create-functions-in-files.html

You will need to keep in mind varible scope. Function only have access to the variables passed in as inputs or that are created inside the function.

[Reem RA]

Thanks a lot Cris.