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*To*: Sascha Ziemann <ceving@x>*Subject*: Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0*From*: Mark H Weaver <mhw@x>*Date*: Sat, 15 Dec 2012 15:10:26 -0500*Cc*: scheme-reports <scheme-reports@x>*In-reply-to*: <878v8z5iq8.fsf@tines.lan> (Mark H. Weaver's message of "Sat, 15 Dec 2012 12:27:11 -0500")*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>

I wrote: > Notationally, 0.0 is an inexact zero and 0 is the exact zero. > Therefore, in Scheme notation, 1.0 (i.e. 1.0+0i) has a different meaning > than 1.0+0.0i. In the case of 1.0, the imaginary part is known to be > exactly zero, whereas for 1.0+0.0i the imaginary part is merely > estimated to be approximately zero. 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. In many (most?) implementations, (imag-part 1.0) => 0.0, which means that some exactness information as been lost. In such implementations, 1.0 and 1.0+0.0i can be treated as equivalent. Mark _______________________________________________ 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:*John Cowan <cowan@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>

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