Run a script 5 times whilst changing the value of one parameter each time.

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Dursman Mchabe 2018-12-17

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https://ww2.mathworks.cn/matlabcentral/answers/436068-run-a-script-5-times-whilst-changing-the-value-of-one-parameter-each-time

评论： Dursman Mchabe 2018-12-19

Repeat.m

Hi everyone

I would like to run the attached script 5 times whilst changing the value of kga from 4e-1 to 4e-2, then 4e-3, then 4e-4, then 4e-5. I would also like to plot the respective results of the repeats on the same set of axis for each respective figure. I would like to ask for help on how to do it.

Regards

Dursman

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Dursman Mchabe 2018-12-19

在 MATLAB Online 中打开

Repeat1.m

Thanks a lot for the comment Madhan. I appreciate. I am not clear about two things:

(1) I am not sure where to put:

for kga =[4e-1, 4e-2, 4e-3 , 4e-4, 4e-5]
    repeat(Repeat1(y,S,kga))
 end

(2) I am also not sure where to and not to pass kga as an input.

After implenting the suggestion (to the best of my limited understanding), I get the following error:

Unable to perform assignment because the left and right sides have a different number of elements.

Error in Repeat1>NSub (line 331)
        discrep(2)      = Rate_gas - Rate_liq ;
Error in Repeat1>@(Tr)NSub(Tr,S,kga) (line 264)
        Tnew               = fsolve (@(Tr)NSub(Tr,S,kga),Trial);
Error in fsolve (line 242)
            fuser = feval(funfcn{3},x,varargin{:});
Error in Repeat1>odes (line 264)
        Tnew               = fsolve (@(Tr)NSub(Tr,S,kga),Trial);
Error in Repeat1>SO2_OdeDriver (line 215)
        dydt                = odes (t, y0,S,kga);
Error in Repeat1 (line 108)
            y               = SO2_OdeDriver(y0,S);
Caused by:
    Failure in initial objective function evaluation. FSOLVE cannot continue.

I have attached a script to my current code.

Stephen23 2018-12-19

编辑：Stephen23 2018-12-19

在 MATLAB Online 中打开

"The automatic response in my mind is to put ... in every local function, except, Repeat1."

And what would that do? Don't just guess or wait for some random stranger to explain what it would do: experiment! Write a few simple local functions in an Mfile, that call each other. Add the same loop to each function. What happens? Does it really do what you want?

Write down the sequence of operations on a piece of paper, or use the debugging tools to track how your code executes: which lines, which functions, etc. Do not just guess and use the shotgun approach.

Tip1: learn another automatic response: less is more.

"Is there any other approach?"

Of course: do not write a recursive function, by NOT calling Repeat1 on line 44 of Repeat1. In your original code (the script attached to your question) the script did not call itself. So why are you doing that now?

Your original question asked "I would like to run the attached script 5 times whilst changing the value of kga ..." and you have been advised by two people to do use a loop, essentially something like this:

for kga = [...]
   ... all of your script (converted to a function) here.
end

And that would indeed resolve your question.

No one advised you to hide loop/s inside your code and then call the function itself on line 44 (and from other locations). For some reason you decided to add loops somewhere inside your code.... of course experimentation is a good thing: thus you have learned that when you call a function from inside itself it leads to recursion. However recursion is not what you want to do to solve this problem.

The loop we showed you should NOT be written anywhere inside Repeat1. That probably means that it should be in its own script (simpler). Or, if you really want all of your code to be in the same file, then create a new main function so that Repeat1 is now just a local function, e.g.:

function out = mymainfun(vec)
num = numel(vec);
out = cell(1,num);
for k = 1:num
    out{k} = Repeat1(vec(k));
end
end
function results = Repeat1(kga)
... all of your code here. No kga loops!
end

Tip2: Start small. Forget about your code. Take this small example and grow it: first just display kga inside Repeat1, then add the other parameter definitions, then add the other local functions, one at a time, passing the parameters properly. Test, Check, Progress.

Stephen23 2018-12-19

编辑：Stephen23 2018-12-19

在 MATLAB Online 中打开

I wrote mymainfun so that you could input any vector of kga values without hardcoding them, which means that you will need to call the function with those values, e.g.:

tmp = [4e-1, 4e-2, 4e-3, 4e-4, 4e-5];
out = mymainfun(tmp);

If you prefer to have have hardcoded values then just get rid of the input argument and write that vector inside the function:

function out = mymainfun()
vec = [4e-1, 4e-2, 4e-3, 4e-4, 4e-5];
num = numel(vec);
out = cell(1,num);
for k = 1:num
    out{k} = Repeat1(vec(k));
end
end
... etc
    

You are the code's designer, so these things are entirely up to you.

Dursman Mchabe 2018-12-19

Thank you so so somuch. The code works 100%. I still have a veery long way to go in learning matlab. But I believe that one day I will be good. I will keep on reading, asking and trying. I thank you so so somuch for everythink that I have learnt yesterday and today.

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