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Solve an expression with fractional exponents

asked 2013-02-27 13:16:53 -0500

adamhg gravatar image

I have an expression which, effectively, looks like this:

expr = x == x^(1/3)*y

except y is a really large number of constants. If I wanted to solve this for x, I should get x=y^(3/2). But instead:

solve(expr,x)

yields

[x == x^(1/3)*y]

In the example I gave, it's obviously not a big deal. But for my actual code, y is a very large number of constant factors, and this means copying those factors out by hand, and then re-inputting them in the correct form ( x = (factors)^(3/2) ) which is error prone and time consuming.

I've tried using 0.333 instead of (1/3) in the exponent, that doesn't make a difference.

Any help here would be appreciated. Thank you ahead of time!

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Just for info - it's not only the `y` that's the problem. `solve(x==x^(1/3),x)` does the same thing. `solve(x==x^(1/3),x,to_poly_solve=True)` solves that problem, but not your question...

kcrisman gravatar imagekcrisman ( 2013-02-27 14:21:00 -0500 )edit

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answered 2013-02-28 02:35:11 -0500

calc314 gravatar image

I tried solve(expr^3,x) and this worked for your simple case.

sage: solve(expr^3,x)

[x == -y^(3/2), x == y^(3/2), x == 0]

I don't know how it will perform with a more complicated expression.

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Asked: 2013-02-27 13:16:53 -0500

Seen: 199 times

Last updated: Feb 28 '13