On Sun, Nov 18, 2012 at 9:02 PM, Shriramana Sharma <samj...@gmail.com>wrote:
> On Sun, Nov 18, 2012 at 8:16 PM, Shriramana Sharma <samj...@gmail.com> > wrote: > > > > ...: summation(lamb[i]*(-1)**(n-j)*binomial(i,n-j),(i,n-j,n)) > > Something like this? >>> var('i j n') (i, j, n) >>> lamb = Function('lamb') >>> Sum(lamb(i)*(-1)**(n-j)*binomial(i,n-j),(i,n-j,n)) Sum((-1)**(-j + n)*lamb(i)*binomial(i, -j + n), (i, -j + n, n)) >>> _.subs(((i,3),(j,4))) Sum((-1)**(n - 4)*lamb(i)*binomial(i, n - 4), (i, n - 4, n)) >>> _.subs(n,6) Sum(i*(i - 1)*lamb(i)/2, (i, 2, 6)) >>> _.doit() lamb(2) + 3*lamb(3) + 6*lamb(4) + 10*lamb(5) + 15*lamb(6) >>> -- 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 sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.