Re: [sympy] solvers - solve(), solve_poly_system

[Mateusz Paprocki]

Hi,

On 10 September 2012 21:04, billpap <bill...@yahoo.gr> wrote:

I have posted my problem already in StackOverflow,

http://stackoverflow.com/questions/12353608/sympy-solve-and-solve-poly-system#comment16590856_12353608

A second problem that I have, is, that although when I use solve_poly_system in gnome terminal

everything it's ok, when I use solve_poly_system in Hadoop streaming, I have the same issue that

I have with solve() when I use it in gnome terminal.

Can you try the most recent version (master branch) from github.com/sympy/sympy? I tried your example and it doesn't work in 0.7.x but works in master. Here is a sample session:

IPython console for SymPy 0.7.1-git (Python 2.7.2-64-bit) (ground types: gmpy)

In [1]: var('r,d,l,k,u,a')

Out[1]: (r, d, l, k, u, a)

In [2]: system = [Eq(r*d, l*k), Eq(u*a, l*k), Eq(k, a*d)]

In [3]: system

Out[3]: [d⋅r = k⋅l, a⋅u = k⋅l, k = a⋅d]

In [4]: solve(system, a, d, l)

Out[4]: 

⎡⎛       _____         _____            ⎞  ⎛      _____        _____           ⎞⎤

⎢⎜      ╱ r⋅u         ╱ r⋅u             ⎟  ⎜     ╱ r⋅u        ╱ r⋅u            ⎟⎥

⎢⎜-k⋅  ╱  ───   -k⋅  ╱  ───        _____⎟  ⎜k⋅  ╱  ───   k⋅  ╱  ───       _____⎟⎥

⎢⎜   ╲╱    k       ╲╱    k        ╱ r⋅u ⎟  ⎜  ╲╱    k      ╲╱    k       ╱ r⋅u ⎟⎥

⎢⎜────────────, ────────────, -  ╱  ─── ⎟, ⎜───────────, ───────────,   ╱  ─── ⎟⎥

⎣⎝     u             r         ╲╱    k  ⎠  ⎝     u            r       ╲╱    k  ⎠⎦

In [5]: solve(system, [a, d, l])

Out[5]: 

⎡⎛       _____         _____            ⎞  ⎛      _____        _____           ⎞⎤

⎢⎜      ╱ r⋅u         ╱ r⋅u             ⎟  ⎜     ╱ r⋅u        ╱ r⋅u            ⎟⎥

⎢⎜-k⋅  ╱  ───   -k⋅  ╱  ───        _____⎟  ⎜k⋅  ╱  ───   k⋅  ╱  ───       _____⎟⎥

⎢⎜   ╲╱    k       ╲╱    k        ╱ r⋅u ⎟  ⎜  ╲╱    k      ╲╱    k       ╱ r⋅u ⎟⎥

⎢⎜────────────, ────────────, -  ╱  ─── ⎟, ⎜───────────, ───────────,   ╱  ─── ⎟⎥

⎣⎝     u             r         ╲╱    k  ⎠  ⎝     u            r       ╲╱    k  ⎠⎦

In [6]: [ eq.subs(zip((a, d, l), _5[0])).simplify() for eq in system ]

Out[6]: 

⎡       _____          _____         _____          _____       ⎤

⎢      ╱ r⋅u          ╱ r⋅u         ╱ r⋅u          ╱ r⋅u        ⎥

⎢-k⋅  ╱  ───  = -k⋅  ╱  ─── , -k⋅  ╱  ───  = -k⋅  ╱  ─── , k = k⎥

⎣   ╲╱    k        ╲╱    k       ╲╱    k        ╲╱    k         ⎦

In [7]: [ bool(eq.subs(zip((a, d, l), _5[0])).simplify()) for eq in system ]

Out[7]: [True, True, True]

In [8]: [ bool(eq.subs(zip((a, d, l), _5[1])).simplify()) for eq in system ]

Out[8]: [True, True, True]

When reporting a problem please include project version number and exact code. Otherwise it's only guessing what's wrong.

Do you have any ideas? 

Thanks in advance.

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Mateusz

[billpap]

Finally, I solved my problem.

The problem was that my program was dependent from the order that some input files were read.

This caused a lot of side effects.

Of course you suggestion about the sympy( github.com/sympy/sympy) helped me a lot to find my issue.

Thanks a lot! Have a nice day.