Forward Euler in JavaScript #418
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| function forward_euler(time_step, n) { | ||
| var arr = []; | ||
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There was a problem hiding this comment. In more modern JS people tend to avoid There was a problem hiding this comment. I think I got behind the usage of var, let and const. After reading about their scopes in the Mozilla Web Dev documents. If I got it right with
Both are only valid for the local control or programming structure, including further inner functions. Thus not globally available to other functions or blocks. There was a problem hiding this comment. @depate Yes, that's pretty much right. Your terminology might not be 100% correct, but I see that you understand the concept. |
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| arr[0] = 1; | ||
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There was a problem hiding this comment. I would just inline this with the array initialization: There was a problem hiding this comment. Ok, if I got this right, this initialises, the I am more used to fixed array dimensions which are allocated or set at the time of the initialisation. So I get confused all the time. But Python also is more 'flexibel' with memory allocation so I could've known better in the first place. |
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| for (var i = 1; i <= n; i++) { | ||
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There was a problem hiding this comment. Same thing about |
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| arr[i] = arr[i - 1] - 3 * arr[i - 1] * time_step; | ||
| } | ||
| return arr; | ||
| } | ||
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| function check_euler(arr, time_step, threshold) { | ||
| var is_approx = true; | ||
| for (var i = 1; i <= arr.length; i++) { | ||
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There was a problem hiding this comment. The range is wrong, it should go from arr.forEach((value, i) => {
// const solution = ...
});There was a problem hiding this comment. Okay, here I get the general concept. One can iterate through the array directly because the array structure supports it as a method internally, great. I am not sure about the As the callback function returns the actual value of the array element, I could "simplify" the following threshold check by passing |
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| var solution = Math.exp(-3 * time_step * i); | ||
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| if (Math.abs(arr[i] - solution) > threshold) { | ||
| alert(arr[i], solution); | ||
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There was a problem hiding this comment. I think a |
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| is_approx = false; | ||
| } | ||
| } | ||
| return is_approx; | ||
| } | ||
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| function main() { | ||
| time_step = 0.01; | ||
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There was a problem hiding this comment. These should all be declared with const timeStep = 0.01;
const threshold = ...; |
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| threshold = 0.01; | ||
| n = 100; | ||
| var euler_result = forward_euler(time_step, n); | ||
| var check_result = check_euler(euler_result, time_step, threshold); | ||
| alert(check_result); | ||
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There was a problem hiding this comment. Similarly to the previous comment, |
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| } | ||
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| main(); | ||
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As a general note, JS uses
camelCasefor everything, so the underscores kind of stand out. I would recommend sticking with the de-facto standard formattingThere was a problem hiding this comment.
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Thanks for the information.
I confess, I did write this first attempt on JavaScript Syntax quite quickly and did not read through a style guide. I could have noticed that there. I'll catch up on the style guides, promise!