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2018-12-16 17:31:44 +0100 received badge  Nice Answer (source)
2018-12-15 13:55:50 +0100 answered a question resolution stuck system polynomials order two

I also raised a question on math.stackexchange about the solvability of my polynomial system. . The Groebner basis method is stuck as well because of the high order of one of the variables ($ch$ which is degree 15).

2018-12-14 13:55:34 +0100 received badge  Teacher (source)
2018-12-14 01:58:38 +0100 answered a question Solve, elegant way ?

Well, I wrote this shorter code :

#PB: Maxime is 32 years old.
#It is twice as old as Albane was when he was the age Albane has now.
#What is Albane's age?
# m = age of Maxime a = age of Albane, x = age difference   
var ('m, x, a')
e1 = m - a == x
e2 = m == 2 * (a-x)
solution = solve([e1,e2],x,a) 
print 'the age of Albane is', solution[0][1].rhs().subs(m=32)

The output is :

$\left[x = \frac{1}{4} \, m, a = \frac{3}{4} \, m\right]$

the age of Albane is 24

2018-12-13 21:47:04 +0100 asked a question resolution stuck system polynomials order two

I have three variables (ISP, ch, $n_C$). I have two equations. My aim is to solve a system of two equations to compute the values of ISP and ch according to $n_C$.

My two equations are polynomials of order two. I put the equations in a framabin :

I tried the solvers of sage and simpy but it does not work. I tried to use Groebner basis but I failed.

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2018-11-16 15:08:42 +0100 commented answer Conversion from symbolic expression to polynomial stuck (I found the page about the Fraction Field Elements.)

AN is my numerator and AD is my denominator of my symbolic expression A. There is not the values of interest (mu and xi_3) in the denominator AD. How should I wrap the whole in the Fraction Field ?

BTW, thank you very much :)

2018-11-16 14:33:05 +0100 received badge  Scholar (source)
2018-11-16 13:57:30 +0100 commented question Conversion from symbolic expression to polynomial stuck (I added a framabin where you can read the symbolic expression.)

2018-11-16 13:31:39 +0100 received badge  Editor (source)
2018-11-16 13:02:24 +0100 asked a question Conversion from symbolic expression to polynomial stuck

I have a very long symbolic expression with six variables:

(E_mu, E_xi3, ISP, T, V_mu, V_xi3, Z, m, mu, n_I, n_P, xi_1, xi_3)

I call the expression AN. I want to convert it in a polynomial of two variables (mu and xi_3). I tried the following command:

AP = AN.polynomial(None,ring=SR['mu,xi_3'])

This works for simple expressions but the command remains stuck for the given expression. My aim is to get the monomials of the polynomial. mu and xi_3 are random variables and I want to compute the expectation of AN (E[AN]). Thus, I could substitute the expectations in the expression.

AN is a numerator, so it is not a fraction. Moreover, I also tried simply_rational but it did not help to convert.

Is there anyway to convert easily ?

EDIT : (I put the symbolic expression in a framabin.)