> From: WF AUTOMACAO <
wfKILLspamAMBIENTE.COM.BR>
> To:
.....PICLISTKILLspam.....MITVMA.MIT.EDU
> Subject: Re: FORTH
> Date: Wednesday, October 07, 1998 3:54 PM
>
> Harold Hallikainen wrote:
> >
> > I haven't used FORTH in a while, but am constantly using my HP
> > 15C and HP35 calculators, both of which operate very in a FORTH manner.
> > FORTH and RPN calculators really DO make sense... You give the machine
> > the numbers, then tell it what to do with them. This is also called post
> > fix notation, as opposed to the in fix notation we're more familiar with.
> > Consider a typical calculator's keystrokes...
> >
> > 2 first argument
> > + I can't add anything yet!
> > 3 second argument
> > = ok, I remember, he wanted to add!
> >
> > On an HP (or FORTH), this would be something like
> >
> > 2 first argument, put on stack
> > 3 second argument, put on stack
> > + Replace two arguments on stack with one result
> > of sum, display
> >
> > Also, most calculators that use algebraic notation often use a
> > mix of RPN and algebraic when they have single argument functions:
> >
> > 2 function argument
> > sqrt do the square root of it
> >
> > This mix of in-fix and post-fix on algebraic calculators can make
> > it fun figuring out which to use when (along with hitting the equals key
> > a half dozen times). With RPN, the calculation proceeds the way you
> > would do it by hand (from the inner most parentheses on out).
> >
> > FORTH is an interesting language, though it tends to be write
> > only (no one else can read it). I've seen some neat algorithms that
> > convert algebraic expressions to FORTH, which can then be easily
> > evaluated by a stack oriented machine.
> > Finally, years and years ago I licensed a 6800 Basic interpreter
> > from Microsoft. It's interesting to see how it evaluates an expression.
> > It actually scans the line left to right, interpreting as it goes along.
> > When it sees some sort of two argument operator (like + ), it goes on and
> > evaluates the second argument, which may involve recursive function
> > calls. It's pretty neat. When it finds a function call, it calls the
> > function evaluator, which then looks at the argument and calls the
> > function evaluator again to evaluate the argument to the function. This
> > continues until there is actually some number that is returned, then all
> > the functions return.
> >
> > So... so much for Forth, RPN, and algebra!
> >
> > Harold
> >
> > Harold Hallikainen
> >
EraseMEharoldspam_OUTTakeThisOuThallikainen.com
> > Hallikainen & Friends, Inc.
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> >
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> If you like Forth, please, do real experiments with Forth 51 at
>
>
http://www.inf.ufsc.br/~jbosco/labvir.htm
>
> Miguel