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Solving for Variable in Mathematica

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Hello,
I am trying to solve a function for the independent variable in Mathematica. I followed the guidelines on this page. And tried this:
Solve[(2 b ((b (1+x))/(y (1-x)+2 b sqrt(1-x^2))-x sqrt((1+x)/(1-x+2 b sqrt(1-x^2)))))/sqrt(1-x^2), x]
But Mathematica said no interpretation was available. Does anyone know why this is not working?I thought it might have something to do with the constant, b, in the function.

Thank you in advance,
Natasha
POSTED BY: Tash Woods
Answer
11 months ago
Hi,

Replace sqrt(...) with Sqrt[...] and add the right-hand side to the equation. It needs to be in the form lhs == rhs.

Youngjoo Chung
POSTED BY: Youngjoo Chung
Answer
11 months ago
If you recieve the message "No Interpretation Available", that means you are using Wolfram|Alpha through Mathematica. This means there is an orange equal sign left of your code. T

When typing out Mathematica code, you will want this to evaluate directly in Mathematica instead. When this is done, there is no orange equal sign to the left of your code. To evaluate a command directly in Mathematica, open a new notebook and type directly into it.

If you are not sure how to evaluate expressions in Mathematica,  please try going through the Mathematica virtual book to learn more about the basics of using Mathematica.

First, begin by going to the documentation for Solve and try evaluating some of the examples. Do you have any problems doing this? Try making some changes to the examples in the documentation for Solve and evaluating them. 
POSTED BY: Sean Clarke
Answer
11 months ago
Hi!
Thank you so much for the pointers. I believe I managed to correct the input:
Solve[(2 b ((b (1 + x))/(c (1 - x) + 2 b Sqrt[1 - x^2]) -
x Sqrt[(1 + x)/(1 - x + (2/b) Sqrt[1 - x^2])]))/
Sqrt[1 - x^2] - y == 0, x]

However, now it is taking 30min+ to run. It is still running. In the meantime, I tried to open another notebook to run some of the other examples and it took quite awhile. It is still computing 2+2. Is this to be expected?

Thank you again,
Natasha
POSTED BY: Tash Woods
Answer
11 months ago
Regarding the issue with running a second notebook, I will direct you to this document on how to set up a second Kernel.  This will allow you to run another computation while one is running.  Assuming you have a dual core and above system.

http://support.wolfram.com/kb/3664

Paul.
POSTED BY: Paul Cleary
Answer
11 months ago
Hi,

I observed that the corrected input is not quite the same as the original. Anyway, if it is taking very long time to solve, it is quite possible that the equation does not have closed-form algebraic solutions. In that case, the solutions can be obtained only numerically using NSolve or FindRoot with given values of the parameters b, c, and y.

While the Mathematica kernel is busy doing some calculation, other pending calculations in the evaluation queue are put on hold. You can abort the on-going calculations by typing Alt+. (Evaluation menu -> Abort Evaluation).

Youngjoo Chung
POSTED BY: Youngjoo Chung
Answer
11 months ago
Great, thank you so much for the pointers! That helps a great deal : )
POSTED BY: Tash Woods
Answer
11 months ago