Hello Aaron, I posted new comments in the git hub you opened. https://github.com/sympy/sympy/issues/19773
Thank you in advance, Javier El mar., 14 de jul. de 2020 a la(s) 21:28, Aaron Meurer ([email protected]) escribió: > Laplace transforms are something that SymPy doesn't do as well with as > it should. I tried to get a closed form version with exponentials by > using apart(full=True) and finding the transform of the individual > terms, but I ran into a bug > https://github.com/sympy/sympy/issues/19773. > > I was able to workaround the bugs to get an answer with > > >>> Add(*[inverse_laplace_transform(nsimplify(i), s, t) for i in > Add.make_args(apart((equ_laplace), s, full=True).doit())]) > (1398726960911182419102898085651241253403000977950623455914670 - > > 24878179654951949422367214210629217423593456535413826921554823*I)*exp(-482231200549273*t/1000000000000000 > - > 283089619304889*I*t/10000000000000000)/100000000000000000000000000000000000000000000000000000000000 > + (1398726960911182419102898085651241253403000977950623455914670 + > > 24878179654951949422367214210629217423593456535413826921554823*I)*exp(-482231200549273*t/1000000000000000 > + > 283089619304889*I*t/10000000000000000)/100000000000000000000000000000000000000000000000000000000000 > - 281057785843441*exp(-177038273656911*t/10000000000000)/10000000000000 > + 65620080368859*exp(-317102332103131*t/10000000000000000)/500000000000000 > > Aaron Meurer > > On Tue, Jul 14, 2020 at 5:37 AM Javier Perez Rodriguez > <[email protected]> wrote: > > > > Hello Aaron, > > > > First of all, thanks for your answer. As you suggested, here I bring a > piece of code with one of the problematic equations (see Section PIECE OF > CODE). As a result of certain computation, I get "equ_laplace" in the > Laplace domain, then, when I try to move it to the Time domain the output > is not a conventional equation (see Section OUTPUT). I have try either > force " sym.inverse_laplace_transform()" not to use Meijerg to compute the > solution or, reshape the Meijerg output to a conventional equation but with > not success yet, unfortunately. > > > > ##### PIECE OF CODE ############ > > import sympy as sym > > > > s = sym.Symbol('s') > > t = sym.Symbol('t', positive=True) > > > > # Equation in the Laplace domain > > equ_laplace = 470.0*s**2/(1.0*s**4 + 18.7*s**3 + 17.9*s**2 + 4.68*s + > 0.131) > > > > # Moving to the Time domain > > equ_time = sym.inverse_laplace_transform(equ_laplace, s, t) > > > > print("equ_time =", equ_time) > > ############################## > > > > #### OUTPUT ################# > > equ_time = 470.0*meijerg(((-16.7038273656911, 0, 0, 0.968289766789687, > 0.517768799450727 - 0.0283089619304889*I, 0.517768799450727 + > 0.0283089619304889*I), ()), ((), (-17.7038273656911, -0.031710233210313, 1, > 1, -0.482231200549273 - 0.0283089619304889*I, -0.482231200549273 + > 0.0283089619304889*I)), exp(t)) > > ############################## > > > > Thank you for your time, > > Javier > > > > -- > > You received this message because you are subscribed to the Google > Groups "sympy" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to [email protected]. > > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/9f0eee0b-4fb6-4303-ba04-17266719fd13o%40googlegroups.com > . > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CAKgW%3D6KVEM_UbdRbVm%2BYOAx7qpuDrKep3C5dCnuPhVqXmpYFMg%40mail.gmail.com > . > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAAAVz-U5OyBhwmvnKMgCwC1tJ2KQQ4mU8FxFAB%3DAwktjXyW_Qg%40mail.gmail.com.
