Suresh, On Tue, Dec 11, 2007 at 09:47:58AM -0800, Suresh Jeevanandam wrote: > > Dear all, > > Let's say I have an expression: > 1/(a+b) > > I want to be able to simplify this to 1/a if we know that a is much, > much greater than b. Is there a way to achieve this already in sympy. > If not, I think this would be a nice feature for engineering people > who would always be making some approximations and get intuitions from > the simplified expressions :)
An example related to your question: In [2]: e = 1/(x+y) In [3]: e Out[3]: 1 ----- x + y In [4]: e.series(y, 1) Out[4]: 1 - + O(y) x You can do it more carefully: if y << x <==> t = y/x << 1, so In [5]: t = Symbol('t') In [6]: et = e.subs(y, t*x) In [7]: et Out[7]: 1 ------- x + t*x In [8]: ets = et.series(t, 1) In [9]: ets Out[9]: 1 - + O(t) x In [10]: ets.subs(t, y/x) Out[10]: 1 - + O(y/x, x, y) x Is that what you need? -- Всего хорошего, Кирилл. http://landau.phys.spbu.ru/~kirr/aiv/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sympy?hl=en -~----------~----~----~----~------~----~------~--~---