Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: HS/Forth
Message-ID: <698.UUL1.3#5129@willett.UUCP>
Date: 22 Mar 90 23:46:15 GMT
Organization: Latest link in the ForthNet chain.  (Pgh, PA)
Lines: 40


 Date: 03-21-90 (23:38)              Number: 58 (Echo)
   To: BILL MCCARTHY                 Refer#: 54
 From: JULIAN NOBLE                    Read: NO
 Subj: MCCARTHY'S TIMINGS            Status: PUBLIC MESSAGE

 Dear Mr. McCarthy,

 I have done some further research into timings, etc. Based on clocks, I
 estimated the minimum time for 25,000 repeats of a=(b+c)/(c+d) to be
 0.63 sec on the 16 MHz 80386/87 combo.  When I hand-coded this (10-byte)
 precision) in assembler, I found the running time (adjusted for clock
 speed) on my machine to be 0.69 sec, really very close to the estimate.

 If Turbo Pascal and Turbo C can really come that close to the minimum
 machine code execution time, they have achieved something no other com-
 piler writer has ever claimed to be able to do.  And, in fact, I doubt
 they have done it.  I bet these compilers removed the invariant
 expression from the loop!  (I know their optimizations include this, and
 it is almost impossible to turn it off.  You can check it by -- say --
 incrementing one of the variables by 1 each time around (or use the in-
 dex as a variable).)

 Nevertheless, you convince me that the overhead in the IFSTACK is too
 great for it to be used to execute the generated FORTH code.  I have
 some ideas that ought to improve things, and will upload a modified
 IFSTACK file when it is ready.

 But finally, I really never intended FORTE to produce production code.
 If you want to program in FORTRAN, get a FORTRAN compiler.  My intent,
 as stated clearly in my Computers in Physics and upcoming JFAR articles
 was to add formula translation to FORTH as a matter of convenience.

 Finally, thank you for your comments.  I appreciate the feedback and
 bug reports.

 Sincerely yours,   Julian V. Noble
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