ASKSAGE: Sage Q&A Forum - Latest question feedhttp://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sun, 09 Dec 2018 13:28:31 -0600Solving linear congruencehttp://ask.sagemath.org/question/44618/solving-linear-congruence/ Is there a simple way to solve a linear congruence modulo an integer with large prime factors in Sage? `solve_mod` function cannot handle such large moduli apparently.kdr01Sun, 09 Dec 2018 13:28:31 -0600http://ask.sagemath.org/question/44618/convert a symbolic var into a numeric varhttp://ask.sagemath.org/question/10359/convert-a-symbolic-var-into-a-numeric-var/Hello,
How to compute y or to draw a point of coord (sol, 0) ?
Thank you
sol=solve(2*x+1==7,x)
print sol
print sol[0], type(sol), type(sol[0])
#y=2*sol+7
#print y
#plot(sol,0)jeanpatWed, 11 Dec 2013 22:09:33 -0600http://ask.sagemath.org/question/10359/How to make solve to use certain variables on the right sidehttp://ask.sagemath.org/question/8247/how-to-make-solve-to-use-certain-variables-on-the-right-side/if I have
I1, IR1, IR2, U1, R1, R2 = var('I1 IR1 IR2 U1 R1 R2')
equations = [
I1 == IR1 + IR2,
IR1 == U1/R1,
IR2 == U1/R2
]
how can I make solve to return
I == (R1 + R2)*U1/(R1*R2)
?
solve(equations, I)
now returns just an empty list
or similait problem is with
I1, IC1, IC2, U1d, U2d, C1, C2 = var('I1, IC1, IC2, U1d, U2d, C1, C2')
equations = [
I1 == IC1 + IC2,
IC1 == C1*U1d,
IC2 == C2*U1d
]
and desired result is
I1 == (C1 + C2)*IC2/C2
OndraFri, 29 Jul 2011 12:56:54 -0500http://ask.sagemath.org/question/8247/Difficulty solving some second order differential equationshttp://ask.sagemath.org/question/10177/difficulty-solving-some-second-order-differential-equations/I have trouble finding 10% and 90% of the rise time in a second order differential equation.
I have tried to search but i have not solved my issue, so now i ask here.
I have added the code to aleph.sagemath.org however the link is crazy long so i put it in a short link: [http://bit.utoft.org/138hfAz](http://bit.utoft.org/138hfAz)
The code is also on pastebin
[http://pastebin.com/4hwdLJuT](http://pastebin.com/4hwdLJuT)
Please help :)
Cheers
J. UtoftjesperFri, 31 May 2013 06:51:05 -0500http://ask.sagemath.org/question/10177/Idea behind not evaluating symbolic equationshttp://ask.sagemath.org/question/8431/idea-behind-not-evaluating-symbolic-equations/Can anyone explain me the following behavior of Sage: What is the idea behind not evaluating symbolic equations which are (obviously) true? For example:
sage: m = var('m')
sage: m == m
m == m
Evaluation works with
sage: bool(m == m)
True
Daniel KrennWed, 02 Nov 2011 23:44:22 -0500http://ask.sagemath.org/question/8431/Solving symbolically equation systemhttp://ask.sagemath.org/question/8242/solving-symbolically-equation-system/I have an equation system:
*U(t) = R * I(t) + L * I'(t) + uC(t)*
*I(t) = C * uC'(t)*
I want to know value of *I'(t)* and *uC'(t)*, which is *(-I(t) * R + U - uC(t))/L* and *I(t)/C* respectively.
In sage I represent it this way:
R = 6; C = 10^(-4); L = 0.1
t = var('t')
U = function('U', t).function(t); I = function('I', t).function(t); uC = function('uC', t).function(t)
equations = [
U == R * I + L * I.diff(t) + uC,
I == C * uC.diff(t)
]
but
solve(equations, I.diff(t), uC.diff(t))
does't seem to be working. (*TypeError: 'sage.symbolic.expression.Expression' object is not iterable*)
why? how can I do this?
OndraSat, 23 Jul 2011 14:24:08 -0500http://ask.sagemath.org/question/8242/