Allegro CL Floating Point

[Stephen Nicoud <snicoud@atc.boeing.com>]

    Date: Thu, 30 Nov 89 15:29:37 EST
    From: maida@cs.psu.edu.ARPANET (Anthony Maida)

    We need to do fast floating point in Lisp. We have benchmarked
    a C program and a Lisp program. Both programs call an exponential
    function and a trig function 250,000 times.

    The C program runs in under 10 seconds. The Lisp program takes
    at least 50 seconds. We can't understand why there should be
    such a discrepancy. Can anyone replicate this and explain the
    discrepancy? 

I don't have a copy of Allegro, but I tried it in Lucid on a Sun 3/60
and it ran in .18 seconds.

> (load "float-test")
;;; Loading source file "float-test.lisp"
#P"float-test.lisp"
;; turn on production compiler
> (proclaim '(optimize (compilation-speed 0)))
T
> (compile 'speed)
SPEED
> (time (speed 500))
Elapsed Real Time = 0.18 seconds
Total Run Time    = 0.18 seconds
User Run Time     = 0.18 seconds
Dynamic Bytes Consed = 0
NIL


When I similary compiled SPEED with just the development compiler,
(proclaim '(optimize (compilation-speed 3))), the execution took about
40 seconds.

Steve