ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Fri, 04 Sep 2020 11:18:45 +0200Finding solution of expression with fractional powerhttps://ask.sagemath.org/question/53299/finding-solution-of-expression-with-fractional-power/I'm trying to solve this equation
$ 3(2.2+(\frac{64}{r})^{(1/3)})= 4(2.2+(\frac{128}{r-1})^{(1/4)})$ using solve function
I want to obtain the numerical solution
**but when i use `sol[0].n(30)`**
**TypeError:** cannot evaluate symbolic expression numerically
**when i try to `find_root(0,1,r)`**
**ValueError:** negative number to a fractional power not real
How to find the solution of this expression ?
deeppaul589Fri, 04 Sep 2020 11:18:45 +0200https://ask.sagemath.org/question/53299/2nd-order ODE: Maxima wants sign of 1 constant before finishinghttps://ask.sagemath.org/question/24624/2nd-order-ode-maxima-wants-sign-of-1-constant-before-finishing/ I'm trying to solve a 2nd-order nonlinear ODE using desolve(). Maxima gets partway through, but then asks for the sign of one of the integration constants. How can I tell it to assume something that doesn't exist before I call desolve()?
t,P,x0=var('t,P,x0')
x=function('x',t)
de=(diff(x,t,2)*x^2+P==0)
forget()
assume(P>0,x0>0)
desolve(de,x,ics=[0,x0,0],ivar=t)
gives the error:
TypeError: ECL says: Maxima asks: Is %k1 positive or negative?
Hoss N. FefferFri, 24 Oct 2014 17:16:29 +0200https://ask.sagemath.org/question/24624/determine consistency of nonlinear system of equationshttps://ask.sagemath.org/question/8540/determine-consistency-of-nonlinear-system-of-equations/Hello,
I need to be able to determine the consistency of very large systems of polynomial equations, with 30-40 variables and as many equations. When I put such systems into ``solve``, I get the same system back again. Here are some equations typical of those in the systems I am dealing with:
``2*a0*b0 == 0,``
``2*a0*b5 + 2*a1*b4 + 2*a4*b1 + 2*a5*b0 - 4*a8*b8 == 0,``
``2*a0*b10 + 2*a1*b9 + 2*a10*b0 + 2*a2*b8 + 2*a8*b2 + 2*a9*b1 == 0,``
``3*b0^2*c6 + 6*b0*b1*c5 + 6*b0*b2*c4 + 6*b0*b4*c2 + 6*b0*b5*c1 + 6*b0*b6*c0 - 12*b0*b8*c9 - 12*b0*b9*c8 + 3*b1^2*c4 + 6*b1*b4*c1 + 6*b1*b5*c0 - 12*b1*b8*c8 + 6*b2*b4*c0 - 6*b8^2*c1 - 12*b8*b9*c0 + 2*a0*a6 + 2*a1*a5 + 2*a2*a4 - 4*a8*a9 == 0``
This is not a complete system - just a few equations to show the lengths of equations that tend to come up. Again, I don't care what any solutions are; I just need to know if any exist. Is there a way to do this in sage?
Thanks!shacsmugglerThu, 08 Dec 2011 14:32:48 +0100https://ask.sagemath.org/question/8540/