I can reproduce this. Seems to be an issue with manualintegrate. Can you
open an issue in the issue tracker for this?
Aaron Meurer
On Thu, Jan 12, 2023 at 12:58 PM Tom van Woudenberg <
tom.van.woudenb...@gmail.com> wrote:
> Hi there,
>
> I'm Tom van Woudenberg, lecturer at Delft University of Technology and I'm
> new to this group. I've got the following problem when trying to solve an
> ODE with a duhamel integral:
>
> import sympy as sp
> omega_n, F_0, m, Omega, zeta = sp.symbols('omega_n, F_0, m, Omega,
> zeta',real=True,positive=True)
> t = sp.symbols('t',real=True)
> u_0, v_0 = sp.symbols('u_0, v_0',real=True)
> omega_1, t_tilda = sp.symbols('omega_1, t_tilda',real=True,positive=True)
> u_forced = sp.simplify(F_0/m/omega_1
> *sp.integrate(sp.sin(Omega*t_tilda)*sp.exp(-zeta*omega_n*(t-t_tilda))*sp.sin(omega_1*(t-t_tilda)),(t_tilda,0,t)))
> print(u_forced)
>
> u_forced takes extremely long (I never got a solution) to find on the
> first run of the cell in a Jupyter Notebook. If it aborted and I run it
> another time, it's found in a couple of seconds:
>
> F_0*(Omega**3*sin(omega_1*t) -
> Omega**2*omega_1*exp(omega_n*t*zeta)*sin(Omega*t) -
> Omega*omega_1**2*sin(omega_1*t) -
> 2*Omega*omega_1*omega_n*zeta*exp(omega_n*t*zeta)*cos(Omega*t) +
> 2*Omega*omega_1*omega_n*zeta*cos(omega_1*t) +
> Omega*omega_n**2*zeta**2*sin(omega_1*t) +
> omega_1**3*exp(omega_n*t*zeta)*sin(Omega*t) +
> omega_1*omega_n**2*zeta**2*exp(omega_n*t*zeta)*sin(Omega*t))*exp(-omega_n*t*zeta)/(m*omega_1*(Omega**4
> - 2*Omega**2*omega_1**2 + 2*Omega**2*omega_n**2*zeta**2 + omega_1**4 +
> 2*omega_1**2*omega_n**2*zeta**2 + omega_n**4*zeta**4))
>
> The same happens in Spyder.
>
> Any ideas of what is causing this issue?
>
> Kind regards,
> Tom van Woudenberg
>
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