Python Problem: "OverflowError: Python int too large to convert to C long"

Question

import sympy as sy
x = sy.symbols('x')
def f2(x,t,l):
    return 5*sy.log(x)+14388/((273+t)*x)-sy.log((1.1910*10**8)/l+1)
print(sy.solve(f2(x,35,80),x))

Result is:

OverflowError: Python int too large to convert to C long

How to solve this problem?

Possible duplicate of stackoverflow.com/questions/38314118/… — Sanil Khurana
– Sanil Khurana, Commented Nov 13, 2019 at 5:08
In Py3, your calculation results in a crash (isympy session killed). Even when I try to scale down the constants. What sort of solution do you expect? — hpaulj
– hpaulj, Commented Nov 13, 2019 at 5:54

smichr · Accepted Answer · 2019-11-13 05:57:03Z

1

Please check your equation. There does not appear to be a solution:

>>> eq=f2(x,35,80);eq
5*log(x) - 14.2134480713559 + 327/(7*x)

There is a minimum in the function and it is convex up at that point and positive:

>>> solve(eq.diff(x))
[327/35]
>>> eq.subs(x,_[0]).n()
1.95961247568333
>>> eq.diff(x,2).subs(x,Rational(327,35))
6125/106929

So if the constant were a little more negative, everything would work:

>>> eq.subs(eq.atoms(Float).pop(),-20)
5*log(x) - 20 + 327/(7*x)
>>> ans=solve(_)
>>> [i.n(2) for i in ans]
[44., 3.3]

answered Nov 13, 2019 at 5:57

smichr

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