how to loop back to the start of a for loop in the middle

Question

Morgan Clendennin 2017-8-31

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https://ww2.mathworks.cn/matlabcentral/answers/354662-how-to-loop-back-to-the-start-of-a-for-loop-in-the-middle

回答： Walter Roberson 2017-8-31

I hope the question I am asking makes sense but I will try and explain it as best I can. If you have any further questions please ask. I am trying to come up with a piece of code that will take certain information that is fed to it, do what I tell the function to do and then if certain conditions are met, it will start running again at a specified part in the code. For example, let's say I have x = 15. Now let's say I define a, b, c, d, and e to be as follows. a = 5, b = 6, c = 8, d = 9, and e = 12. I want to run a piece of code that will do the following steps:

1. Check to see if x - a >= 0
2. If x - a >= 0, x = x - a.
3. Check to see if x - a is still >= 0
4. If x - a >= 0, x = x - a.
5. if x - a < 0, check to see if x - b >= 0.
6. if x - b >= 0, x = x - b.
7. Check to see if x - b is still >= 0.
8. if x - b >= 0, repeat steps 4 - 7 using b and c now.
9. repeat the previous steps 1- 8 for c, d and e.
10. if x - e < 0, do nothing or values remain the same.

I want these steps to work for any amount of re-loops meaning if x = 15 and a = 5 then x - a will occur 3 times but if x = 10 it will occur twice and if x = 20, it will occur 4 times, and so on. I don't want this to be a piece of code where it checks if the stated conditions above are met a pre-defined number of times but rather it will check it dynamically and will re-enter the loop as many times as necessary. If this is needed to re-enter the beginning of the loop and automatically bypass the conditions it doesn't meet that is acceptable. By this I mean let's say we're on step 6 above. We do step 6 and then check in step 7. If we need to re-loop back to step 1 and automatically bypass steps 1 - 4, then that's fine.