[e-lang] Is it done?

Ben Laurie benl at google.com
Tue Jan 1 08:16:31 EST 2008


On Jan 1, 2008 1:14 PM, Ben Laurie <benl at google.com> wrote:
> On Jan 1, 2008 7:34 AM, Mark Miller <erights at gmail.com> wrote:
> > On Dec 31, 2007 9:54 PM, Kevin Reid <kpreid at mac.com> wrote:
> > > > (mismatch (file #P"/Users/erights/svn-other/e-on-cl/tests/
> > > > numbers.updoc")
> > > >           (source "def x := 2.0 ** -0.5")
> > > >           (expects ("value" "0.7071067811865476"))
> > > >           (instead ("value" "0.7071067811865475")) (opt-backtrace
> > > > nil))
> > >
> > > This is the floating-point problem I mentioned. I believe that
> > > 0.7071067811865475 is actually the correct answer; please verify this.
> >
> > E-on-Java does give 0.7071067811865475. For this case, E-on-Java
> > simply delegates to Java's StrictMath.pow(), which is supposed to use
> > IEEE double precision with round-to-even. I'm not sure what else to do
> > to verify this.
>
> $ bc
> bc 1.06
> Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
> This is free software with ABSOLUTELY NO WARRANTY.
> For details type `warranty'.
> scale=100
> 1/sqrt(2)
> .7071067811865475244008443621048490392848359376884740365883398689953\
> 662392310535194251937671638207863

Alternatively, this shows which is righter:

0.7071067811865476*0.7071067811865476-.5
.00000000000000010691335120706576
.5-0.7071067811865475*0.7071067811865475
.00000000000000003450800503024375


>
>
> > Since this kind of thing may be sensitive to platform issues at
> > several levels of abstraction, for the record, my "rune --version"
> > prints
> >
> > E version: 0.9.1c at /Users/erights/ehome/
> > on Java version: 1.5.0_07 at
> > /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home
> > on OS: Mac OS X version: 10.4.11 on i386 (mac/x86)
> > for erights in US
> >
> >
> >
> > --
> > Text by me above is hereby placed in the public domain
> >
> >     Cheers,
> >     --MarkM
> >
> > _______________________________________________
> > e-lang mailing list
> > e-lang at mail.eros-os.org
> > http://www.eros-os.org/mailman/listinfo/e-lang
> >
>


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