Re: Just comments about math

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On 2001 December 7 12:34 pm, Edipo Elder Fernandes de Melo wrote:

> =# select (3+0.2*707/80)*80;
>  ?column?
> ----------
>     381.4
>
> =# SELECT 80*(3+(707/80)*0.2);
>  ?column?
> ----------
>       368
>
>     Answer: "select 707/80;" returns 8, while "select 707/80::float"
> returns 8.8375.

SELECT 707.0/80;  --> 8.8375
 In your first expression, you change type to floating point in your first 
operation, but in your second expression  you don't change type until the 
second to last operation.  Integer division always returns an integer result, 
even when it's not the most mathematically intuitive way to do things.

- -- 
Andrew G. Hammond     mailto:drew@xyzzy.dhs.org   http://xyzzy.dhs.org/~drew/
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"To blow recursion you must first blow recur" -- me
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