Thanks for your answer. However : this was a simplified example in a larger context. The values can be arbitrary (for example generated by numerical random number generator) and so the use of rationnal is not practical ... I knew about the fact that simplify is not a in-place method, the last line of my previous code was a mistake (however it did not change the result displayed for this time). Sorry about that. Thanks again, Mike
Le vendredi 31 juillet 2020 01:43:18 UTC+2, Oscar a écrit : > > Have you tried using exact Rational values instead of floats? For example > 1e-6 could be Rational(1, 10**6) or S(1)/10**6. It is best to avoid using > floats if possible. > > Also simplify is not an in-place method so you need to use: > H3 = H3.simplify() > rather than > H3.simplify() > > -- > Oscar > > On Sun, 26 Jul 2020 at 21:56, Mikhael Myara <mikhae...@umontpellier.fr > <javascript:>> wrote: > >> Something weird, I would like to understand why. >> >> After some computations I reach a quite complex expression : >> >> [image: Capture d’écran 2020-07-26 à 22.49.18.png] >> >> >> >> From that I run the following code : >> >> import sympy as sp >> >> H=-(-CB*Ve*s*(-CA*s - 1/RA)**2/(RB*(CB*s + 1/RB)*(CA*s - (-CA*s - 1/RA)** >> 2/(CA*s - CB**2*s**2/(CB*s + 1/RB) + CB*s + 1/RA) + 2/RA)*(CA*s - CB**2*s >> **2/(CB*s + 1/RB) + CB*s + 1/RA)) - CB*Ve*s/(RB*(CB*s + 1/RB)))/(Ve*(CA*s >> - CB**2*s**2/(CB*s + 1/RB) + CB*s + 1/RA)) >> >> H1=H.subs({RB:1e3,CA:1e-6}) >> display(H1) >> H1.simplify() >> display(H1) >> >> H2 = H.simplify() >> display(H2) >> H3=H2.subs({RB:1e3,CA:1e-6}) >> H3.simplify() >> display(H3) >> >> >> And I obtain what follows. I am surprized that inserting values instead >> of some symbols disables sympy simplification. In some more complex cases, >> the computation times required for simplification are huge and lead to non >> simplified expressions. >> >> >> Any idea why ? >> >> >> Best regards, >> >> Mike >> >> [image: Capture d’écran 2020-07-26 à 22.54.31.png] >> >> >> >> -- >> 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 sy...@googlegroups.com <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/sympy/5622efd3-9718-4d8b-b5cb-373235ab7d42o%40googlegroups.com >> >> <https://groups.google.com/d/msgid/sympy/5622efd3-9718-4d8b-b5cb-373235ab7d42o%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- 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 sympy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/2b798f1e-1c3b-4788-a64b-4a9cd8a05febo%40googlegroups.com.