Ticket #869 (closed defect: fixed)
atan/log/sqrt failures
Reported by: | dfindlay | Owned by: | gb |
---|---|---|---|
Priority: | normal | Milestone: | |
Component: | ANSI CL Compliance | Version: | trunk |
Keywords: | Cc: |
Description
The sqrt, log and atan functions are failing over significant portions of their domain (particularly for rational or complex rational arguments), even when it is entirely reasonable that a good result should be returned. Some typical examples are:
(sqrt (expt 10 47)) => 3.1622778E+23 ;CCL errors (sqrt (/ (expt 10 47) 3)) => 1.8257418E+23 ;CCL errors (sqrt (complex (expt 10 46) (expt 10 47))) => #C(2.3505187E+23 2.12719E+23) ;CCL errors (sqrt (complex most-positive-short-float most-positive-short-float)) => #C(2.0267142E+19 8.394926E+18) ;CCL errors (log (expt 10 -66)) => -151.97063 ;CCL errors (log (- (expt 10 66))) => #C(151.97063 3.1415927) ;CCL returns wrong type (double, not single) (log (complex (expt 10 65) (expt 10 66))) => #C(151.9756 1.4711276) ;CCL errors (log (complex (expt 10 -65) (expt 10 -66))) => #C(-149.66307 0.09966865) ;CCL errors (log 8.0d0 2) => 3.0D0 ;CCL returns wildly inaccurate result (log #C(0.0 1.0) 0) => #C(0.0 0.0) ;CCL returns wrong type (integer) (atan (expt 10 46) (expt 10 47)) => 0.09966865 ;CCL errors (atan (expt 10 -46) (expt 10 -47)) => 1.4711276 ;CCL returns zero
I'm attaching a file that demonstrates how these could all be fixed by making changes to CCL's sqrt, log, log-e and atan functions (but the changes may not be implemented in the most efficient way). Making these fixes would also have a knock-on effect and correct dependent infelicities in both the arg and phase functions (which aren't noted above).
Attachments
Change History
Changed 6 years ago by dfindlay
- attachment fn-ticket.lisp added
comment:3 Changed 6 years ago by dfindlay
I've tried (but possibly not completely succeeded) to come up with some sort of "reference" implementation for CL's math functions. Of course, the problems originally mentioned are fixed (and there aren't some of the obvious bugs in the previous attachment - sorry), and a few other problems are identified.
You could you this in two ways. Either you could use it to test an upgraded CCL implementation. Or you could just use the implementation as CCL's.
Just loading the attached file will give some key comparison's between the "reference" implementation and CCL's.
Changed 6 years ago by dfindlay
- attachment ccl-math-reference.lisp added
"Reference" implementation of math functions
comment:4 Changed 4 years ago by gb
- Owner changed from rme to gb
- Status changed from new to assigned
comment:5 Changed 4 years ago by gb
- Status changed from assigned to closed
- Resolution set to fixed
(In [15683]) Implement the rest of Dave Findlay's "reference" math library. Fixes ticket:869 in the trunk.
sqrt/log/atan changes [demo]