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sympydifferential-equations

expecting ints or fractions, got % and % in sympy

I need to solve differential equation y'=6e^(2x-y). I am trying to do that in sympy with dsolve().

sol = dsolve(Derivative(f(x), x) - 6 *(e**(2*x-f(x))), f(x))

But always get error

expecting ints or fractions, got 7.38905609893065022723042746058 and 6

What is the problem?

Solution

  • Where did you get e from? It seems you used math.exp(1) or similar to get a floating point value that the symbolic package can not treat correctly

    Using sympy.exp instead works perfectly, even defining e=sympy.exp(1) is correctly recognized. Both with the result 

    Eq(f(x), log(C1 + 3*exp(2*x)))