Function name has to be same as file name?

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Khadeja Khan
Khadeja Khan 2020-5-9
评论： Leo Stocco 2022-12-17
Hi, I have a .m file called randomStep, and within the file I want to have a function called randomStep. However, when I name the function randomStep, it isn't running the program but giving me an error saying: Function 'randomStep' has already been declared within this scope. When I change the name to randomStep2 it works fine and runs the program. When creating functions, aren't the functions supposed to have the same names as the file? I also want to be able to call the randomStep function in another file, which isn't working for me. Any help would be appreciated greatly. Below is a copy of my randomStep function, which is saved inside a file called randomStep.m:
[x,y]=randomStep2([103.2, 203.1, 500],[45.2, 0.1, 20],400,400,20)
function [x,y] = randomStep2(x,y,xMax,yMax,speed)
N=normrnd(0,1,1,length(x));
for i=1:length(x)
if(x(i)+N(i)*speed)>xMax
x(i)=xMax-mod(x(i),xMax);
elseif(x(i)+N(i)*speed)<0
x(i)=abs(x(i)+N(i)*speed);
else
x(i)=x(i)+N(i)*speed;
end
end
N=normrnd(0,1,1,length(y));
for j=1:length(y)
if(y(j)+N(j)*speed)>yMax
y(j)=yMax-mod(y(j),yMax);
elseif(y(j)+N(j)*speed)<0
y(j)=abs(y(j)+N(j)*speed);
else
y(j)=y(j)+N(j)*speed;
end
end
disp([x])
disp([y])
end
  1 个评论
Leo Stocco
Leo Stocco 2022-12-17
Is there any way to force Matlab to generate a warning message when it runs a function does not have the same name as the filename? This causes me problems when I accedentally misname a function since it can sometimes get "found" somewhere else in my matlab search path and cause unexpected results that can be really tricky to debug.

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Matt J
Matt J 2020-5-9
编辑：Matt J 2020-5-9
When creating functions, aren't the functions supposed to have the same names as the file?
No. If your mfile is a function file, then it is good practice (but not necessary) for the top level function to have the same name as the file. Your mfile is in any case not a function file. It is a script,
https://www.mathworks.com/help/matlab/matlab_prog/scripts-and-functions.html
within which you have attempted to define randomStep as a local function. A local function should not have the same name as the file.
For an mfile to qualify as a function file, then its only purpose should be to define a function and the first line in the file must declare the input/output syntax of that function:
function [x,y] = randomStep(x,y,xMax,yMax,speed)
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Matt J
Matt J 2020-5-9
Thank you! That worked :)
You're welcome. Since it did work, though, please Accept-click the answer.
but I also want its outputs of [sSeries, iSeries,rSeries] to be within the same m file as where the function is defined?
Then you would make singleSimulation a local function inside that mfile. However, singleSimulation will then only be invokable within that file and not elsewhere. (Although, you could create a function handle to singleSimulation and use that to invoke the function indirectly).
Should the function be a different name to the m file in that case?
Yes.
Khadeja Khan
Khadeja Khan 2020-5-10
Hey Matt, I have another seperate question which I posted about my loops not working correct, and it seems like I need my r count to not decrease to prevent those who are recovered from being re infected. Could you please take a look at it and possibly give some suggestions about how I may implement such an r count? Thanks so much.

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