Re: Doubt about formula transcription

"James Giles" <jamesgiles@[EMAIL PROTECTED]
> wrote in message
news:RYOKj.156005$cQ1.70133@[EMAIL PROTECTED]
"glen herrmannsfeldt" <gah@[EMAIL PROTECTED]
> wrote in message
[elided]

> OK. So your advice is that we *do* have to worry about
> things that were resolved in the 1960's.  Note that commutativity
> and associativity have always been *mathematically* correct,
> so Fortran compilers have always been allowed to use them
> for optimization.  And I know I saw people doing it in the late
> 1960's.

It's certainly do***ented before 1970 - the XPL compiler
being one where those optimisations were carried out.

The IBM FORTRAN H compiler for the System 360
(1966) was noted for the high degree of optimisation,
though whether it commuted operands I don't know,
but I would be surprised if it didn't.

Another of the period, the IBM PL/I Optimising
compiler (c. 1969), produced good code, but
(as in the case of the H compiler), I can't say whether
those specific optimisations were carried out.
Likewise, I would be surprised if it didn't.

IBM's PL/I-F compiler (1966) also did limited optimisations.