Re: Terminology question - for the professors

Posted by Joel on September 11, 2002 at 18:49:58:

In Reply to: Re: Terminology question - for the professors posted by Jonathan Burros on September 11, 2002 at 11:35:24:

: : 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:

• No...because it becomes f(n) after summation (n/t) Subhotosh Khan 08:02:52 09/12/02 (5)
  • 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)

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