You can find plenty of discussion on this issue at https://code.google.com/p/v8/issues/detail?id=3006.
Note that 64-bit doubles have 15-16 decimal digits of precision, so you have (best case): -3.16836290305272216816234731596E-1 <--significant--><---random---> The new implementation trades a bit of precision for much more speed. Since the JS specification does not make any guarantees about precision, this is not a bug. That said, there's some hope that we'll find a better speed/precision compromise in the future. On Wed, Feb 26, 2014 at 10:22 PM, Erik Neumann <[email protected]>wrote: > I should add that on my system, running the same test under Safari and > Firefox is still returning the correct result of 0xBFD4470BB84303C9. Only > Chrome is failing. > --ErikN > > On Wed, Feb 26, 2014 at 1:11 PM, Erik Neumann <[email protected]> wrote: > >> In Chrome Version 33.0.1750.117 the Math.cos() function is returning >> different and less accurate results. >> >> Specifically Math.cos(-1.89318839074561684476805112354) should be >> -3.16836290305272216816234731596E-1 but is now returning >> -3.16836290305271717215873650275E-1 instead. >> >> This has changed since early February with Chrome version 32.0.1700.102. >> >> I am running on Mac OS X 10.9.1 with 16 GB of memory. >> >> Some more details: The double hex values involved are: >> angle = 0xBFFE4A7FE8F6B56D = -1.89318839074561684476805112354 >> According to mathematica (or Wolfram Alpha) the result should be: >> -0.31683629030527219006269881180 >> The nearest double hex value is 0xBFD4470BB84303C9 = >> -3.16836290305272216816234731596E-1 >> And that is the result I was previously getting in Chrome version 32. >> >> But we are getting now: >> >> 0xBFD4470BB84303C0 = -3.16836290305271717215873650275E-1 >> >> This is significantly different, and is a problem for my application. >> > > > -- > -- > v8-users mailing list > [email protected] > http://groups.google.com/group/v8-users > --- > You received this message because you are subscribed to the Google Groups > "v8-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/groups/opt_out. > -- -- v8-users mailing list [email protected] http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
