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wanted: opinions on a benchmark.
- To: MOON at MIT-MC
- Subject: wanted: opinions on a benchmark.
- From: George J. Carrette <GJC at MIT-MC>
- Date: Fri, 6 Mar 81 19:52:00 GMT
- Cc: BUG-LISP at MIT-MC, BUG-LISPM at MIT-MC, NIL-I at MIT-MC
- Original-date: 6 March 1981 14:52-EST
Thanks for the explaination.
About the divide-by-zero and overflow errors. What I really want
is some kind of arithmetic modulo M. However, the description of
24-bit-arithmetic in the Lispm-Manual scared me off a bit.
What would be very nice is to be able to use the same generic
arithmetic functions, "+","*","//","\", with a "small fixnum"
which had certain properties, amoung them "staying small."
It is not that I don't like SMALL-FLONUM's, it is just that
the algebraic properties of them are not ideal for hidden-line
clipping arithemetic. What happens is that because the
lisp machine does a lot more CHECKING, this forces the program
using them to do checking too, and to compensate for the strange
algebraic properties. Its pretty obvious that if one can get
the required program behaviour from the properties of the objects
being manipulated, rather than from hairy control structure inside
the program itself, then it is a win.
The Array-accessing problem: Of course, the Maclisp object I used
to descibe a CLIPPING-PLANE was a fixed-size hunk, a very simple
structure fixed locations of which can be referenced with a single
Lispm-machine arrays have much more complex properties, which simplify
the control structure of many of the programs which use them no doubt!