summation over tuple of symbols

[Nova Munch]

hello.

i have a tuple of symbols, a where a is (a_0, a_1, a_2, a_3, a_4)

i want to call:

>> summation(a[i], (i, 0, 4))

but python returns a TypeError that the indices must be integers, not Symbol. 

this is more of a python constraint instead of Sympy. but is there some workaround to it?

thanks folks!

[Sudhanshu Mishra]

Hi Nova

Since `a` is a python tuple, you can not access its elements by passing a symbol as index.

`summation` can be used like this:

>>> summation(2*i - 1, (i, 1, n))

Hope this helps.

​Regards​

​Sudhanshu Mishra​

www.sudhanshumishra.in

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[Sergey Kirpichev]

Hmm.  I have no idea of what you want, but...

In [32]: A = IndexedBase('A')

In [33]: n=Symbol('n', integer=True)

In [34]: Sum(A[n],(n,0,2))
Out[34]:
  2      
 ___     
 ╲       
  ╲   A[n]
  ╱      
 ╱       
 ‾‾‾     
n = 0    

In [35]: _.doit()
Out[35]: A[0] + A[1] + A[2]

[Nova Munch]

hello! 

yes. i think thats very close to what i am looking for. 

thank you!