MathGroup Archive 2004

[Date Index] [Thread Index] [Author Index]

Search the Archive

Using "Sum" (i = 1 ... N) in a function definition

I was trying to define a function using the Sum command in the
following way (simplified example):

 MyData = {3,2,4,5,6};
 MyFunc[i_] = Sum[MyData[[j]],{j,1,i}];

As you can see, the idea is to use the length of the list (i)
as a variable in the function definition, such that

 MyFunc[1] = 3
 MyFunc[2] = 3 + 2 = 5
 MyFunc[3] = 3 + 2 + 4 = 9

etc. Mathematica does not like the abobe statements, and prints the
following error message:

"Part specification K$394 is neither an integer nor a list of

Does anybody know how to define (correctly) such a function. Should be
possible ...?

  • Prev by Date: Re: DeleteCases : several at once, conditions
  • Next by Date: Re: Long function defintions
  • Previous by thread: Re: RE: Combinations
  • Next by thread: Re: Using "Sum" (i = 1 ... N) in a function definition