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* [Bug math/2154] New: accuracy of cacoshl is bad.
@ 2006-01-15 18:02 aj at suse dot de
2006-04-25 18:43 ` [Bug math/2154] " drepper at redhat dot com
0 siblings, 1 reply; 3+ messages in thread
From: aj at suse dot de @ 2006-01-15 18:02 UTC (permalink / raw)
To: glibc-bugs
Adding these tests to math/libm-test.inc's cacosh_test gives upto 770 ULPs for
the long double tests:
TEST_c_c (cacosh, 0.3, 0.4, 0.405112337178030872507338405200229579L,
1.29016676450309079292712537938218583L);
TEST_c_c (cacosh, -0.3, 0.4, 0.405112337178030872507338405200229579L,
1.85142588908670244553551800389731705L);
TEST_c_c (cacosh, 0.3, -0.4, 0.405112337178030872507338405200229579L,
-1.29016676450309079292712537938218583L);
TEST_c_c (cacosh, -0.3, -0.4, 0.405112337178030872507338405200229579L,
-1.85142588908670244553551800389731705L);
the float and double tests pass, just long double has this problem.
--
Summary: accuracy of cacoshl is bad.
Product: glibc
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: math
AssignedTo: drepper at redhat dot com
ReportedBy: aj at suse dot de
CC: glibc-bugs at sources dot redhat dot com
GCC build triplet: x86_64-linux-gnu
GCC host triplet: x86_64-linux-gnu
GCC target triplet: x86_64-linux-gnu
http://sourceware.org/bugzilla/show_bug.cgi?id=2154
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* [Bug math/2154] accuracy of cacoshl is bad.
[not found] <bug-2154-131@http.sourceware.org/bugzilla/>
@ 2012-02-22 22:22 ` jsm28 at gcc dot gnu.org
0 siblings, 0 replies; 3+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2012-02-22 22:22 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=2154
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|SUSPENDED |RESOLVED
Resolution| |INVALID
--- Comment #2 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-02-22 22:22:26 UTC ---
The tests given in this bug take the double constants 0.3 and 0.4 and convert
them to long double. The results of cacoshl appear to be within a few ULPs of
what is expected for those particular long double values, whereas the
expectations given in this testcase are the results for infinite-precision
constants 0.3 and 0.4 (as opposed to those for values rounded to 53 bits then
extended to 64 bits, or rounded directly to 64 bits) - and when your inputs
differ by 11 bits from what they were intended to be, 770 ULPs is hardly an
unexpected error. So this is not a correct test and there is no sign of undue
inaccuracy here (I don't think it's yet expected for complex functions to be
last-bit-accurate correctly rounded).
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2006-01-15 18:02 [Bug math/2154] New: accuracy of cacoshl is bad aj at suse dot de
2006-04-25 18:43 ` [Bug math/2154] " drepper at redhat dot com
[not found] <bug-2154-131@http.sourceware.org/bugzilla/>
2012-02-22 22:22 ` jsm28 at gcc dot gnu.org
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