While loop question - working with vectors - Сообщения
I am trying to write a while loop that will iterate for a variable until a certain user-defined error tolerance is reached. I started by writing the loop for a single element, and got it working fine. When I then tried to make it work using vectors, it goes through one iteration then stops. I have attached my loop as it stands; for example, the first value of m after iteration should be 0.243, not 0.183.
I am starting to think I need a nested for loop, but to be honest, I am a bit behind times when it comes to programming...
Any help is appreciated, and thanks in advance!
While Loop Not Working.sm
BTW, looking at the Error array, it looks like there is an issue at row 2.
While Loop Not Working.sm
Best regards.
Alvaro.
While playing with my simple while loop, I figured out that assigning m the value from the previous iteration is not the way to go. What works better is to start with m=0 and add a small increment (say, 0.001) to it with each iteration (so the new m=m+0.001). Theoretically, m needs to be between 0 and 1 so this is fine.
That said, when I try to implement that approach into the loop with the vectors, it just blows through all the iterations and does not stop at the specified Error threshold... I need to spend some more time and figure out what is going on.
While playing with my simple while loop, I figured out that assigning m the value from the previous iteration is not the way to go. What works better is to start with m=0 and add a small increment (say, 0.001) to it with each iteration (so the new m=m+0.001). Theoretically, m needs to be between 0 and 1 so this is fine.
For a general numerical procedure to minimize or find roots the guess initial value is part of the problem start data, not a result of some reasoning, except that you study the behavior of some particular function.
For example for solving f(x) = 0, f(x) = 1 - x^2 starting with x = 0.5 you usually get x = 1, and with x = -0.5 results x = -1. That means that you must know something about the solution before starting a numerical procedure.
In your case your m independent variable is not scalar, but vectorial. You can't add m+0.01 ... you must add 0.01 for each component looking to all combinations, which actually could be done, but is a kind of brute force method. Usually you know something about the desired result and use that to select "good" guess values for each component.
That said, when I try to implement that approach into the loop with the vectors, it just blows through all the iterations and does not stop at the specified Error threshold... I need to spend some more time and figure out what is going on.
Not stopping just because of an issue with m[2]. The Error for other components decreases very quickly. Just check if it needs a different guess value or why with the values of the others variables it not converges to a solution.
Best regards.
Alvaro.
0.234,0.522,0.564,0.524,0.528,0.527,0.535,0.564,0.614,0.621
Not stopping just because of an issue with m[2]. The Error for other components decreases very quickly. Just check if it needs a different guess value or why with the values of the others variables it not converges to a solution.
Best regards.
Alvaro.
It seems it is not just the issue with m[2]. The values calculated by that loop are not the correct ones; the correct values should be:
0.234,0.522,0.564,0.524,0.528,0.527,0.535,0.564,0.614,0.621
It would help showing your conclusive solving system
While Loop.sm
It seems it is not just the issue with m[2]. The values calculated by that loop are not the correct ones; the correct values should be:
0.234,0.522,0.564,0.524,0.528,0.527,0.535,0.564,0.614,0.621
It would help showing your conclusive solving system
While Loop with Vectors.sm
Attached is the loop that works.
Next two things ... plot m, spline
plot m indexed x ... cinterp
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