使用 sympy 重新排列方程式？

Question

Im trying to rearrange a supply curve equation for calculation the price elasticy.

The equation is log P = -2 + 1.7 * log Q .

Im trying to rearrange the equation so that log Q is in terms of log P. Is there a way sympy can handle these rearrangements?

p, q = sp.symbols('p, q', real=True, positive=True)

eq = sp.Eq(-2+1.7*sp.log(q))

sp.solve(eq,sp.log(p))

Answer 1

Using sympy solve will take care of the arrangements. The equations just must be set up properly and the function parameters must be correct.

import sympy as sp

p, q = sp.symbols('p, q', real=True, positive=True)
eq = sp.Eq(-2+1.7*sp.log(q), p) # set equation = to p
ans = sp.solve(eq,q) #solve equation for q in terms of p

This solution simply saves your equation to eq and solves eq for q so the answer is in terms of only p. In the end ans holds the value:

[3.24290842192454*exp(0.588235294117647*p)]

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Answer 2

Although you showed log P in the written text, you did not include it in the code. If you do so, you can then request that solve isolate log(q) for you:

>>> eq = Eq(log(p), -2 + 10*log(q)/17)
>>> solve(eq, log(q))
[17*log(p)/10 + 17/5]