On Sat, Feb 23, 2008 at 11:05 PM, Ben Goodrich <[EMAIL PROTECTED]> wrote: > > Hi, > > Pursuant to > > > http://groups.google.com/group/sage-support/browse_thread/thread/f05932c2048f0ac0/ > > I am now trying to solve a system of equations using sympy instead of > Maxima to see if sympy's behavior is closer to that of Mathematica. > > The following example is from the sympy tutorial (where it works fine > in regular sympy) but is not included in the the Sage documentation on > how to use the sympy interface. Can someone explain what is wrong? > > sage: var('x y') > sage: from sympy import solve, Symbol > sage: x = Symbol("x") > sage: y = Symbol("y") > sage: solve(x**4 == 1, x) # fine > [I, 1, -1, -I] > sage: solve([x + 5*y == 2, -3*x + 6*y == 15], [x, y]) # error > --------------------------------------------------------------------------- > <type 'exceptions.ValueError'> Traceback (most recent call > last) > > /media/sda4/sage-2.10.2/<ipython console> in <module>() > > /media/sda4/sage-2.10.2/local/lib/python2.5/site-packages/sympy/ > solvers/solvers.py in solve(eq, syms, simplified) > 98 equ = eq[i].lhs - eq[i].rhs > 99 else: > --> 100 equ = Basic.sympify(eq[i]) > 101 > 102 content = collect(equ.expand(), syms, > evaluate=False) > > /media/sda4/sage-2.10.2/local/lib/python2.5/site-packages/sympy/core/ > basic.py in sympify(a, sympify_lists) > 267 pass > 268 if a.strip() != a: > --> 269 return Basic.sympify(a.strip()) > 270 raise ValueError("%r is NOT a valid SymPy expression" > % a) > 271 > > /media/sda4/sage-2.10.2/local/lib/python2.5/site-packages/sympy/core/ > basic.py in sympify(a, sympify_lists) > 268 if a.strip() != a: > 269 return Basic.sympify(a.strip()) > --> 270 raise ValueError("%r is NOT a valid SymPy expression" > % a) > 271 > 272 @Memoizer('Basic', MemoizerArg((type, type(None), tuple), > name='type'), return_value_converter = lambda obj: obj.copy()) > > <type 'exceptions.ValueError'>: '6 y - 3 x == 15' is NOT a valid SymPy > expression > sage: > > For some reason, it gets transformed into '6 y - 3 x == 15' instead of > '6*y - 3*x == 15' . > > Thanks,
Hi Ben, thanks for spotting this problem. I created an issue for this: http://code.google.com/p/sympy/issues/detail?id=722 We are making a new release of sympy today, so I'll try to fix this problem too and finally create a new Sage sympy spkg. Ondrej --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
