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| /freebsd-11-stable/lib/msun/src/ | ||
| H A D | e_powf.c | diff 129955 Tue Jun 01 17:03:31 MDT 2004 bde Fixed another precision bug in powf(). This one is in the computation [t=p_l+p_h High]. We multiply t by lg2_h, and want the result to be exact. For the bogus float case of the high-low decomposition trick, we normally discard the lowest 12 bits of the fraction for the high part, keeping 12 bits of precision. That was used for t here, but it doesnt't work because for some reason we only discard the lowest 9 bits in the fraction for lg2_h. Discard another 3 bits of the fraction for t to compensate. This bug gave wrong results like: powf(0.9999999, -2.9999995) = 1.0000002 (should be 1.0000001) hex values: 3F7FFFFF C03FFFFE 3F800002 3F800001 As explained in the log for the previous commit, the bug is normally masked by doing float calculations in extra precision on i386's, but is easily detected by ucbtest on systems that don't have accidental extra precision. This completes fixing all the bugs in powf() that were routinely found by ucbtest. |
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