SymPy.solvers.solve() returns empty list

Question

While using sympy.solve() to try and solve simple linear equations, the function just returns an empty list.

Here is my code:

from sympy import Symbol
from sympy.solvers import solve
from sympy.parsing.sympy_parser import parse_expr as parse 

x = Symbol('x')
equation = input('Enter an equation: ')
equation = message.content.split()[1].replace('=',',')
solution = solve(parse(equation))

For equation = 'x+3=8', print(solution) just prints []

Can anyone figure out why this is happening?

Thanks!

Asked By: 433MEA

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Source

Answer 1

I’m not sure what the best practice here is, but using Eq here will work.
The code after a few changes-

from sympy import Symbol, Eq
from sympy.solvers import solve
from sympy.parsing.sympy_parser import parse_expr as parse

x = Symbol('x')
equation_1 = input('Enter an equation: ')
equation_2 = equation_1.split('=')
solution = solve(Eq(*[parse(i) for i in equation_2]), x)
print(solution)

example output-

Enter an equation: x+1=x**2
[1/2 - sqrt(5)/2, 1/2 + sqrt(5)/2]

Answered By: Guy

Answer 2

The standard way to handle this parsing is to use the "battery" transformations:

>>> from sympy.parsing.sympy_parser import parse_expr, T
>>> parse_expr('x=1',transformations=T[1,9]) # auto-symbol and convert =
Eq(x, 1)
>>> solve(_)
[1]

Answered By: smichr

SymPy.solvers.solve() returns empty list

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