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*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*: Fri, 21 Dec 2012 00:53:15 -0500*Cc*: scheme-reports <scheme-reports@x>*In-reply-to*: <87d2y5y6fb.fsf@tines.lan>*References*: <878v8z5iq8.fsf@tines.lan> <874njn5b65.fsf@tines.lan> <20121215204015.GG13463@mercury.ccil.org> <87obhv3ts0.fsf@tines.lan> <20121215231548.GC10312@mercury.ccil.org> <87bodu4r0r.fsf@tines.lan> <20121216041031.GE10312@mercury.ccil.org> <87pq25yh5s.fsf@tines.lan> <20121219221955.GH4477@mercury.ccil.org> <87d2y5y6fb.fsf@tines.lan>

Mark H Weaver scripsit: > Yes, that's exactly what I mean. I know that SCM and Gauche do this, > and I suspect it's quite common. Okay, the details are at ComplexRepresentations now. Racket, Kawa, Chez, Vicare, Larceny, Ypsilon, !IronScheme, Spark support (imag-part 2.0) => 0 even though they don't support mixed-exactness complex numbers. > >> Another test that would be worthwhile is this: > >> > >> (list (eqv? +0.0 -0.0) > >> (eqv? (make-rectangular +0.0 1.0) > >> (make-rectangular -0.0 1.0)) > >> (eqv? (make-rectangular 1.0 +0.0) > >> (make-rectangular 1.0 -0.0)) > >> > >> I wouldn't be surprised if some Schemes distinguish signed zeroes in the > >> real part but not in the imaginary part. If an implementation discards > >> inexact zero imaginary parts, then it probably discards the sign as well > >> as the exactness. The results here weren't interesting: they were all either (#t #t #t) or (#f #f #f), or throwing an error on undefined `make-rectangular`, with the sole exception of Vicare, which returns (#t #f #f). However, this version does not properly defend against systems which interpret `-0.0` as just another spelling of 0.0 even though they support negative zero internally. I may attempt that later, though I doubt the results will be any more interesting. My guess is that `make-rectangular` always returns a boxed or unboxed pair of numbers whatever the values may be on every system that supports complex numbers at all. -- A mosquito cried out in his pain, John Cowan "A chemist has poisoned my brain!" http://www.ccil.org/~cowan The cause of his sorrow cowan@x Was para-dichloro- Diphenyltrichloroethane. (aka DDT) _______________________________________________ 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:*Per Bothner <per@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:*Alex Shinn <alexshinn@x>

**References**:**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>

**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:*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:*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:*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:*Mark H Weaver <mhw@x>

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