ratio between variables in equation

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robin johansson
robin johansson on 18 Dec 2016
Commented: robin johansson on 19 Dec 2016
I have the equation G == (f_1*(w^2)*L/d)+(C*(w^2))/2
Where d and w are variables and f_1, L, G and C are constants
I would like to arrange this equation in the form of w*(d^2) == constants but i only know how to solve for individual variables with syms
How would i go about this?

Answers (1)

John D'Errico
John D'Errico on 18 Dec 2016
Well, you might want to do that, but if both w and d are unknowns, then even if you do it with pencil and paper, you won't succeed.
You would be closer if you had asked to solve for the form w^2/d than w*d^2, but even that will fail. Note that w appears only as w^2. And only one of those terms is divided by d. So, first factor out w^2.
G = w^2*(f_1*L/d + C/2)
You can trivially solve for w^2.
w^2 = G/(f_1*L/d + C/2)
In fact, you can trivially solve for w, by taking the square root as long as you are willing to choose which branch of the square root applies.
But nothing will allow you to get that expression in the form w/d^2, with no d terms on the right hand side. Wanting magic to happen is not sufficient. No symbolic computational engine will do the mathematically impossible either.
  1 Comment
robin johansson
robin johansson on 19 Dec 2016
Yes how silly of me, i suspected it was mathematically impossible but wanted to make sure.

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