Re: [Axiom-mail] sum()

[Daniel Yokomiso]

On Tue, 22 Jun 2004 08:59:04 +0000, Martin Rubey <martin> escreveu:

> De: Martin Rubey <martin>
> Data: Tue, 22 Jun 2004 08:59:04 +0000
> Para: Marcus Better <marcusb>
> Assunto: Re: [Axiom-mail] sum()
> 
> You tried: 
> 
>  >    f: Integer -> Integer;
>  >    f(0)==1; f(1)==2;
>  >    f(n)==sum(f(i)*f(n-i), i=0..(n-1))
> 
> Try
> 
> f: Integer -> Integer;                
> f(0)==1; f(1)==2;                     
> f(n)==reduce(+,[f(i)*f(n-i) for i in 1..(n-1)])
> 
> I have no good explanation why sum won't work.

"sum" doesn't work because your definition is different. The original has "i" 
ranging from 0 to (n - 1), while yours ranges from 1 to (n - 1). Using "i" from 
0 makes the definition incorrect.

> (Well, I know why it happens
> internally. I'm looking for a solution...)
> 
> Martin

    Best regards,
    Daniel Yokomizo.