[sage-support] Re: Multiplicity of solutions

2009-06-06 Thread Michael Friedman
Hi all thanks for the answers. Here is simple example. It's in fact intersection of two projective curves: a cuspidal cubic curve y^2*z-x^3=0 and its polar w.r.t. (2:1:1) : 2*y*z + y^2 - 2*3*x^2. when substituting z=1 i used: solve([y^2-x^3==0, 2*y +y^2 -2*3*x^2==0], x, y). The general case wil

[sage-support] Re: Multiplicity of solutions

2009-06-06 Thread John Cremona
Can the original poster provide a (simple) example of the kind of set of equations he wants to solve? For example, are they polynomials in several variables, or more exotic? In the case of polynomial equations it is more likely that (perhaps via Singular) the multiplicities can be obtained. Joh

[sage-support] Re: Multiplicity of solutions

2009-06-06 Thread simon . king
Hi! On 6 Jun., 05:45, Robert Dodier wrote: > CVS log claims this bug was fixed recently (between 5.17 & 5.18). > Here's what I get with Maxima from CVS (5.18+). > > ... Very good! So, ticket #6228 can be closed when the new maxima version is in Sage. But I think we should now come back to the

[sage-support] Re: Multiplicity of solutions

2009-06-05 Thread Robert Dodier
Marshall Hampton wrote: > sage: z = var('z') > sage: f5 = (z^5-1)^2 > sage: f5.roots() > > [(e^(2/5*I*pi), 2), > (e^(4/5*I*pi), 2), > (e^(-4/5*I*pi), 1), > (e^(-2/5*I*pi), 1), > (1, 2)] > > Odd, very odd. I guess one of us should write about this on the > maxima list. CVS log claims this bu

[sage-support] Re: Multiplicity of solutions

2009-06-05 Thread Marshall Hampton
Its a puzzling pattern as to which multiplicities are incorrect: sage: z = var('z') sage: f5 = (z^5-1)^2 sage: f5.roots() [(e^(2/5*I*pi), 2), (e^(4/5*I*pi), 2), (e^(-4/5*I*pi), 1), (e^(-2/5*I*pi), 1), (1, 2)] Odd, very odd. I guess one of us should write about this on the maxima list. -Ma

[sage-support] Re: Multiplicity of solutions

2009-06-05 Thread simon . king
Oops. On 5 Jun., 21:32, simon.k...@uni-jena.de wrote: >   sage: E=(z^3-1)^3 >   sage: e = E==0 >   sage: m=e._maxima_() >   sage: m.solve(z).str() >   '[z=(sqrt(3)*%i-1)/2,z=-(sqrt(3)*%i+1)/2,z=1]' Here I forgot to copy-and-paste the line sage: P = m.parent() >   sage: P.get('multiplicities')

[sage-support] Re: Multiplicity of solutions

2009-06-05 Thread simon . king
Hi! I should add that the bug occurs for sage 4.0. Is it still there in 4.0.1? It seems that the problem is in maxima. Looking at the code, solve does the following: sage: E=(z^3-1)^3 sage: e = E==0 sage: m=e._maxima_() sage: m.solve(z).str() '[z=(sqrt(3)*%i-1)/2,z=-(sqrt(3)*%i+1)/2,z=

[sage-support] Re: Multiplicity of solutions

2009-06-05 Thread simon . king
Dear Marshall On 5 Jun., 21:07, Marshall Hampton wrote: > That's pretty disturbing because those complex roots should have > multiplicity 3. So, I was right that the multiplicities where a bit odd... :) > Is this a known bug? I searched in trac. There used to be two open tickets mentioning mu

[sage-support] Re: Multiplicity of solutions

2009-06-05 Thread Marshall Hampton
That's pretty disturbing because those complex roots should have multiplicity 3. Is this a known bug? -Marshall Hampton On Jun 5, 1:05 pm, simon.k...@uni-jena.de wrote: > Hi Michael, > > On 5 Jun., 18:26, Michael Friedman wrote: > > > I'm pretty new to Sage, so I'm sorry in advance for the tri

[sage-support] Re: Multiplicity of solutions

2009-06-05 Thread simon . king
Hi Michael, I am sorry for my previous reply. I think I missed one word in your question: On 5 Jun., 18:26, Michael Friedman wrote: > I'm pretty new to Sage, so I'm sorry in advance for the trivial > question. > I have a set of (non-linear) equations, and I need to find the multiplicity

[sage-support] Re: Multiplicity of solutions

2009-06-05 Thread simon . king
Hi Michael, On 5 Jun., 18:26, Michael Friedman wrote: > I'm pretty new to Sage, so I'm sorry in advance for the trivial > question. > I have a set of (non-linear) equations, and I need to find the > multiplicity of each solution. How do I do it? First of all, solving a nonlinear eqution is not