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Topic: Reason for operator precedence
Replies: 15   Last Post: Mar 15, 2006 8:56 AM

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Dik T. Winter

Posts: 7,899
Registered: 12/6/04
Re: Reason for operator precedence
Posted: Mar 14, 2006 8:31 AM
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In article <1142342196.542632.294210@i39g2000cwa.googlegroups.com> matt271829-news@yahoo.co.uk writes:
> Tony wrote:
...
> > I was wondering what the reason is for having multiple levels of operator
> > precedence?

...
> As far as addition/subtraction vs multiplication/division is concerned,
> one reason is to ensure that the distributive property of
> multiplication works sensibly. For example, we want 3*(4 + 6) = 3*4 +
> 3*6 = 3*(6 + 4) = 3*6 + 3*4.
>
> And for exponentiation we want, for example, 3*3^2 = 3^3, not (3*3)^2


That is not the reason. You could just as well have left to right
operation when you use sufficiently many parenthesis in the euqations.
E.g. 3*(4 + 6) = (3*4) + (3*6).

But try to write the polynomial x^7 + 2x^6 - 3x^5 + 2x^4 +7x^3 - 3x^2 - 5x + 8
without assuming precedence. It is to avoid large numbers of parenthesis.
--
dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, +31205924131
home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/




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