[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

*To*: Mark H Weaver <mhw@x>*Subject*: Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0*From*: John Cowan <cowan@x>*Date*: Sat, 15 Dec 2012 15:40:16 -0500*Cc*: scheme-reports <scheme-reports@x>*In-reply-to*: <874njn5b65.fsf@tines.lan>*References*: <8738zc9g2x.fsf@tines.lan> <CAMMPzYOKcOm+trYA0Fc+NtWfG00K0BM4hvghsxrr6L9wnCyhuQ@mail.gmail.com> <87d2yf80q3.fsf@tines.lan> <20121214223854.GX29857@mercury.ccil.org> <CAGUt3y55KEVFn=6_i9yRXR8w_e8Nk2tN7QGCF8rEhYTs2Xgrjw@mail.gmail.com> <878v8z5iq8.fsf@tines.lan> <874njn5b65.fsf@tines.lan>

Mark H Weaver scripsit: > I should mention that Scheme implementations differ in how hard they > work to preserve exactness information. For example, (log 1) and > (sin 0) might return either 0 or 0.0 depending on the implementation, > and (imag-part 1.0) might return either 0 or 0.0. That behavior is licensed by the wording of R5RS/R7RS 6.2.2, which permits non-rational operations to produce inexact results even if exact results are possible. > In many (most?) implementations, (imag-part 1.0) => 0.0, Both behaviors are licensed by 6.2.2. Rational operations on inexact numbers can produce exact results (but are not required to) if the exact number can't affect the results. ComplexRepresentations explains which Schemes support and don't support exact complex numbers and complex numbers of mixed exactness (which are considered inexact by R7RS). -- In my last lifetime, John Cowan I believed in reincarnation; http://www.ccil.org/~cowan in this lifetime, cowan@x I don't. --Thiagi _______________________________________________ Scheme-reports mailing list Scheme-reports@x http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports

**Follow-Ups**:**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Mark H Weaver <mhw@x>

**References**:**[Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Mark H Weaver <mhw@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Alex Shinn <alexshinn@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Mark H Weaver <mhw@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*John Cowan <cowan@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Sascha Ziemann <ceving@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Mark H Weaver <mhw@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Mark H Weaver <mhw@x>

- Prev by Date:
**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0** - Next by Date:
**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0** - Previous by thread:
**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0** - Next by thread:
**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0** - Index(es):