[Webkit-unassigned] [Bug 115553] New: SunSpider 1.0: 3d-morph: use epsilon to check result

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=115553

           Summary: SunSpider 1.0: 3d-morph: use epsilon to check result
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Unspecified
        OS/Version: Unspecified
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: Tools / Tests
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: ctruta at gmail.com


3d-morph.js fails on QNX. The testOutput is expected to be a number that starts with a 6, but the actual output is approx. -4.97e-14.

I reimplemented 3d-morph in C, and I executed it both with double and long double on x86_64 Linux.
By using double calculations and sin(), the result was 6.75e-14.
By using long double calculations and sinl(), the result was -6.279e-14.

Is the theoretical result supposed to be zero, and the actual one closed to zero, due to error accumulations?

Running the same program on ARM QNX, the result (using double and sin()) was -4.97e-14, i.e. same as inside JSC.

Then I looked at all intermediate results returned by sin(). Out of 240 distinct calls to sin(), about ~65 of them are different by exactly 1ULP. In my understanding, that error should be acceptable.

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