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20th January 2019, 02:15 #1
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computing roots on a calculator
currently calculators accept square roots as sqrt(9) which is 3
but how to change the root so as to compute a cube root or more than 3rd roots?

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20th January 2019, 02:53 #2
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Re: computing roots on a calculator
A basic method to take cube root of 9:
* take log(9)
* divide by 3
* take antilog
A scientific calculator has a button to calculate X to the Y power. The cube root of 9= (9)^1/3 power.
Or a button to calculate #Xth root of Y.
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20th January 2019, 05:23 #3
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20th January 2019, 05:41 #4
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Re: computing roots on a calculator
It cannot be done (in a single step) on a basic calculator; but the search bar calculator is quite powerful.
You can type either ** or a ^ as the power symbol (operation). In other words, x**y and x^y means the same: x raised to the power of y.
If the power is integer you simply type it as such. For roots (say cube roots) you need to type 1/3 in parenthesis: 27^(1/3) will give you 3.
Internally, the numeric processor uses an algorithm very similar to the one pointed out in post #2. If both x and y are floats, x^y is computationally very expensive in time (it does take lots of time or cpu cycles).
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20th January 2019, 06:28 #5
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Re: computing roots on a calculator
They should implement
crt(x) cube root
qrt(x) quad root
currently only sqrt(x) is implemented.

20th January 2019, 09:21 #6
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Re: computing roots on a calculator
The nth root of a number x can be found by x^(1/n). If you have the xpowertime button, then you use it.
   Updated   
It has already been implemented. But it's dynamic, so you can select the power you wish yourself. That is what has been done with the x^y function.
Akanimo.
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20th January 2019, 09:33 #7
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Re: computing roots on a calculator
qrt(x) quad root
If you are familiar with Newton Raphson method, you can use that for many different problems.
The real problems are (float)^(float) they are hard to manage numerically.
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21st January 2019, 05:18 #8
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21st January 2019, 09:32 #9
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Re: computing roots on a calculator
As documented, bc ^ operator supports only integer power arguments. e(l(x)/3) however works. You can define it as a function if you like. Or use a somewhat more elaborated calculator.
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