No...because it becomes f(n) after summation (n/t)

Posted by Subhotosh Khan on September 12, 2002 at 08:02:52:

In Reply to: Re: Terminology question - for the professors posted by Joel on September 11, 2002 at 18:49:58:

: : : Is a Sum statement properly termed a "function"
: : : so that EITHER of the following:

: : : f(n) = n(n+1)/2
: : : and
: : : f(n) = Sum[from n=1 to n]n

: : : BY ITSELF would be correctly considered a function that defines the series {1,3,6,10,15...} ?

: : : The former, of course, is a quadratic function. What is the latter? Is it a propositional function?

: : You wrote the latter

: : f(n) = Sum[from n=1 to n]n

: : wrong

: : It should be

: : f(n) = Sum[from j=1 to n]j

: : Then f(n)= n(n+1)/2

: : Yes f(n)=n(n+1)/2 defines the series

: : {1,3,6,10,15...}

: :

: Hmmm... now that you pointed it out I agree that
: f(n) = Sum[from n=1 to n]n
: seems to have too many n's.

: But I don't think your f(n) = Sum[from j=1 to n]j looks right either.

:
: Shouldn't it be:
: f(j) = Sum[from j=1 to n]j ?

Follow Ups:

• Very confusing... Joel 09:57:08 09/12/02 (4)
  • Re: Very confusing... T.Gracken 13:42:44 09/12/02 (2)
    • ah, recursion ... Joel 17:48:47 09/12/02 (1)
      • Re: ah, recursion ... T.Gracken 21:34:08 09/12/02 (0)
  • keep after 'em, Joel....I'm learning too! I automatically get nervous every time I see the "sigma summation formula" ! Denis Borris 10:59:23 09/12/02 (0)

Post a Followup