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Message-ID: | <46D5AD5A.B110DBB6@dessent.net> |
Date: | Wed, 29 Aug 2007 10:31:06 -0700 |
From: | Brian Dessent <brian AT dessent DOT net> |
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CC: | cygwin AT cygwin DOT com, newlib AT sourceware DOT org |
Subject: | Re: 1.5.24: sin() bug |
References: | <20070829153331 DOT GA95558 AT tetsuo DOT karasik DOT eu DOT org> <46D5A79E DOT C09EF7CE AT dessent DOT net> <003201c7ea5f$d01db8f0$2e08a8c0 AT CAM DOT ARTIMI DOT COM> |
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Dave Korn wrote: > Since when was pi less than 2^-27? This is a kernel sin, a function over the limited range [-pi/4, pi/4], where the general case sin is reduced to kernel sin by the remainder of modulus pi/2. > I think it may be an artefact of FP precision and/or rounding mode, but I'd > need to do more experiments to make sure. OTOH it could be an artifact of the > printf %g specfier. Like I said, more experimentation is needed! A problem with the testcase is the .10. It helps to expand that so that you see the entire value. Or use %a. newlib returns 3CED1A62633145C0 whereas both MSVCRT and x86 linux seem to return 3CED1A6000000000. It sort of looks like a truncation problem but since glibc agrees with msvcrt (shock!) I tend to think the latter is right. The actual mantissas are: newlib 1.1101000110100110001001100011001100010100010111000000 other 1.1101000110100110000000000000000000000000000000000000 Brian -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
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