[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 106
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Есть такая задачка.
Предложите функцию, которая бы имела следующие свойства:
1. F(x=0) = 0
2. F(x) << 1 на интервале [0, a]
3. F(x) монотонно возрастает на интервале [a, b]
4. F(x) -> 1 ассимптотически при x >b
Хочу сделать машку с "хорошим" поведением. Желательно чтобы функция была алгебраической, т.е. без тригонометрии, логарифмов и экспонент.
If for practical purposes, make a table + approximator to it. It is also convenient for experiments.
If it is algebraic, then it is not a polynomial (condition 4 is violated), but the ratio of two polynomials of equal powers.
I have to think about it.
I don't want any arctangents. MT4 counts all trigonometry, logarithms and exponents very slowly.
And the ratio is exactly what I think it is but I cannot think of a suitable one.
Извините что встреваю. Но какой раз не гляну на вашу ветку, так то 1050-ое сообщение на 105 странице, то 1010 на 101-ой. Мистика какая-то...:)))
Reload the browser by deleting the nearest history. And there will be less mystique.
Electric wire and household wire are significantly different things. If this is a task and not the reasoning of an electrician, then electric wire means a conductor, without all the TVs, irons, stranding, three-phase and other nonsense. And where have you seen the direct current that powers all these household appliances? The trick is to understand the geometry of the magnetic field of a rectilinear direct current. If the compass was "lying on the wire" rather than facing it, the arrow would be perpendicular to the wire.
Yurixx, electrical wires can be single-core or multi-core, example: http://www.elcable.ru/product/catalog/mark.html?mark=121
That was the trick of the task. You should have thought it was single-core, such as: http://www.elcable.ru/product/catalog/mark.html?mark=85
If you're not happy with the definition of "household wire", then take some "clearly not household" cable, for example: http://www.elcable.ru/product/catalog/mark.html?mark=23
Indeed, household appliances are not powered by DC, but by AC, I pointed that out in the condition for simplicity. Incidentally, on AC high frequency current a compass may not detect the field even in the case of a single wire.
If for practical purposes, make a table + approximator to it. It is also convenient for experiments.
You need a characteristic function that defines the smoothing parameter depending on one or at most two parameters of price behaviour. If it is analytical, then by changing its parameters we can study the method and if it is effective, we can use it to set up the tool.
And what will the table give me? I don't know where the values should be. Not to mention trying different variants. After all, there are as many points as there are degrees of freedom. I only need 1 or 2.
Арктангенсов не хочется. В МТ4 вся эта тригонометрия, логарифмы и экспоненты очень медленно считаются.
А отношение - это как раз то, что и я думаю, но как-то подходящее в голову не приходит.
I got pictures similar to what you want, when I experimented with sigmoid.
Look at the function of the form y=x*(x^(n-1))/(1+abs(x^n)), add the necessary offsets and coefficients on the input and output and you'll be happy. In the simplest case n=1.
Reload the browser by deleting the nearest history. And there will be less mystique.
The mystique will remain. This forum has 10 posts per page.
Yurixx, electrical wires can be single-core or multi-core, example: http://www.elcable.ru/product/catalog/mark.html?mark=121
That was the trick of the task. You should have thought it was single-core, such as: http://www.elcable.ru/product/catalog/mark.html?mark=85
If you're not happy with the definition of "household wire", then take some "clearly not household" cable, for example: http://www.elcable.ru/product/catalog/mark.html?mark=23
Indeed, household appliances are not powered by DC, but by AC, I pointed that out in the condition for simplicity. Incidentally, on AC high frequency current a compass may not detect the field even in the case of a single wire.
Do you come up with these problems yourself or do you get them from somewhere ?
If the former, you should formulate them more carefully. The task is not to mislead the solver, but to "give food for thought".
If the second, I assure you that no household wire was or could be implied there. Look at the answer.