On Sun, Nov 18, 2012 at 3:03 PM, Shriramana Sharma <[email protected]> wrote:
> I'll be back with more queries later. :-)
OK so here's my next query on the same thread:
In [1]: from sympy import *
...: i,j=symbols('i j',integer=True)
...: lamb=list(symbols('lamb:4'))
...: n=3
...: summation(lamb[i]*(-1)**(n-j)*binomial(i,n-j),(i,n-j,n))
...:
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
/mnt/sda7/samjnaa-precise/<ipython-input-1-0af017dc9283> in <module>()
3 lamb=list(symbols('lamb:4'))
4 n=3
----> 5 summation(lamb[i]*(-1)**(n-j)*binomial(i,n-j),(i,n-j,n))
6
TypeError: list indices must be integers, not Symbol
OK so since lamb is a Python list and not a SymPy list (is there such
a thing?) Python tries to dereference it using i and throws the error.
Basically I want to do a summation of lamb0 ... lamb3 with the
appropriate coefficients. What to do?
Thanks!
--
Shriramana Sharma
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