Nope.
Using `sympy` through `sage` :
```
sage: reset()
sage: t=var("t")
sage: B=function("B")
sage: Eq=-B(t)^2-B(t).diff(t)+1==0
sage: import sympy
sage: Sol=sympy.dsolve(*map(sympy.sympify, (Eq, B(t))))._sage_() ; Sol
B(t) == -1/tanh(C1 - t)
sage: C1=var("C1")
sage: foo(t)=Sol.rhs()
sage: bool(Eq.substitute_function(B, foo))
True
sage: bar(t)=tanh(C1-t)
sage: bool(Eq.substitute_function(B, bar))
False
```
HTH,
Le lundi 4 avril 2022 à 00:39:41 UTC+2, kang.mat...@gmail.com a écrit :
> There is an issue in the sympy.dsolve module. When I was trying to solve
> the ode: -B(t)^2 - B'(t) +1 =0. The proper result should be tanh(C_1 - t),
> while the given result is the 1/tanh(C_1 - t).
>
> I can help to solve this issue as a GSOC project if provided the
> permission from the community. I often use the sympy package, and I love it
> as it is a competitive alternative to the Wolfram Mathematica.
>
> And I am now a master's student at the Mathematical Institute, Oxford
> University. Before coming here, I possess a computer science undergraduate
> degree. Here is my Linkdin
> <https://www.linkedin.com/in/kang-li-84949a154/>.
>
> [image: IMG_7136.jpg]
>
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