Re: A slow summation

Thanks Bill - all of those examples work fine.  Pity about the slow list,
though.

-Alasdair

On 6/14/07, Bill Page <[email protected]> wrote:
>
> Of course these also make some sense :-)
>
> (1) -> sum(1/x,x=1.0..20000.0)
>
>    (1)  10.4807282172 29327571
>                                   Type: Union(Expression Float,...)
> Time: 0.02 (IN) + 3.10 (EV) + 0.02 (OT) + 0.32 (GC) = 3.45 sec
>
> (2) -> sum(1/x,x=(1.0..20000.0)$Segment DoubleFloat)
>
>    (2)  10.480728217229315
>                          Type: Union(Expression DoubleFloat,...)
>                           Time: 1.77 (EV) + 0.23 (GC) = 2.00 sec
>
> (3) -> sum(1/x,x=1..20000)::Float
>
>    (3)  10.4807282172 29327573
>                                                                   Type:
> Float
>                          Time: 5.02 (EV) + 1.22 (GC) = 6.23 sec
>
> ----------
>
> Float is the domain of finite precision floating point numbers and
> DoubleFloat is the domain of hardware support floating point numbers.
> The last computes an exact fraction (rational number) with a final
> conversion to Float.
>
> Maybe they provide good examples for your students?
>
> Regards,
> Bill Page.
>

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