On 20 Feb 2005, at 8.01 am, Mark J. Reed wrote:

> On Sat, Feb 19, 2005 at 02:18:38PM -0500, # 1 wrote:
>> I've tried as hard as I could but I'm totally unable to understand
>> how does
>> works a stack-based syntax
>
> Well, it's probably easiest to start with stack-based arithmetic; then
> the extension to language may make more sense.
>
> Consider an arithmetic expression like this:
>
>         1 + 2 × 3 - 4 ÷ 5
>
> Anyone past middle school has learned that there is a standard order of
> operations in such expressions.  In English, we learn the phrase "My
> Dear Aunt Sally" to remember that Multiplication and Division come
> before Addition and Subtraction.  To change the order, or just to make
> it explicit, you can use parentheses (...), which say "do what's
> between us first".  The above is the same as this:

I've never heard 'My Dear Aunt Sally' before; well, not in reference to
maths. I was taught in grade five the more complete 'bodmas'; my sister
was taught 'Bomdas' (but 'Bodmas' seems to have been more common; my
subsequent two schools, at least, and the textbooks I used, said
'Bodmas'. Not very often, mind, but they did). The variation is of
course because multiplication and division and addition and subtraction
are equal in precedence, and whether you prefer 2×4/3 as (2×4)/3 or
2×(4/3) is irrelevant to the answer .

It stands for Brackets, Order, Divide, Multiply, Add, Subtract; this
specifies (in addition to the fact that you do division and
multiplication before addition and subtraction) that brackets over-ride
everything else, and powers come before multiplication (so that 2×3^4
is 2×(3^4), not (2×3)^4). Bodmas is introduced before powers are.

--
Tristan.