I believe the reason you are not getting a solution (originally) is related to https://github.com/sympy/sympy/issues/8789 .
On Friday, January 16, 2015 at 1:20:49 PM UTC-6, Junwei Huang wrote: > > Thanks very much, Chris. That solves the problem. > > On Fri, Jan 16, 2015 at 2:09 PM, Chris Smith <[email protected] > <javascript:>> wrote: > >> (actually, you don't need to factor, but doing so shows the quadratic >> nature of the thing). I get for approx. solutions, +/- 2.6. >> >> On Friday, January 16, 2015 at 1:06:18 PM UTC-6, Chris Smith wrote: >>> >>> The expression is quadratic in C0 only if C0 is positive. Try replace C0 >>> with var('x', positive=True); factor the result, *then* solve for your two >>> values. >>> >>> On Wednesday, January 14, 2015 at 4:44:28 PM UTC-6, Junwei Huang wrote: >>>> >>>> Hi all, I have a symbolic expression as in polyC >>>> >>>> In [46]: polyC >>>> Out[46]: -(sqrt(2035953389603699)*sqrt(-1/C0**12)/2000000 - >>>> 4849598923/(54000000*C0**6))**(1/3) - 1 + 3599/(300*C0**2) - >>>> 368417/(18000*C0**4*(sqrt(2035953389603699)*sqrt(-1/C0**12)/2000000 - >>>> 4849598923/(54000000*C0**6))**(1/3)) >>>> >>>> In [47]: N(polyC,2) >>>> Out[47]: -(23.0*(-1/C0**12)**0.5 - 90.0/C0**6)**0.33 - 1.0 + 12.0/C0**2 >>>> - 20.0*(23.0*(-1/C0**12)**0.5 - 90.0/C0**6)**(-0.33)/C0**4 >>>> >>>> In [48]: polyC.simplify() >>>> Out[48]: -1 - (54*sqrt(2035953389603699)*sqrt(-1/C0**12) - >>>> 9699197846/C0**6)**(2/3)/(600*(27*sqrt(2035953389603699)*sqrt(-1/C0**12) >>>> - 4849598923/C0**6)**(1/3)) + 3599/(300*C0**2) - >>>> 368417*2**(1/3)/(60*C0**4*(27*sqrt(2035953389603699)*sqrt(-1/C0**12) - >>>> 4849598923/C0**6)**(1/3)) >>>> >>>> In [49]: solve(polyC.simplify(),C0) >>>> Out[49]: [] >>>> >>>> In [50]: solve_poly_system([polyC.simplify()],C0) >>>> PolynomialError: C0**(-2) contains an element of the generators set >>>> >>>> >>>> But if you exam Out[46], polyC seems to be something like >>>> C0**2*(expr)-1. then C0 can be solved with two roots. Anything I missed? >>>> Thank you. >>>> >>> -- >> You received this message because you are subscribed to a topic in the >> Google Groups "sympy" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/sympy/AI6kqPjhVkA/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> [email protected] <javascript:>. >> To post to this group, send email to [email protected] <javascript:> >> . >> Visit this group at http://groups.google.com/group/sympy. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/sympy/53665b8e-973a-4a6e-be8f-dc14d973441b%40googlegroups.com >> >> <https://groups.google.com/d/msgid/sympy/53665b8e-973a-4a6e-be8f-dc14d973441b%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/d/optout. >> > > -- 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 post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/f557de9e-843f-4448-889f-6970ffc7378b%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
