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*To*: Aubrey Jaffer <agj@x>*Subject*: Re: [Scheme-reports] Numerical example (real? -2.5+0.0i)*From*: John Cowan <cowan@x>*Date*: Sun, 2 Oct 2011 01:48:00 -0400*Cc*: scheme-reports@x*In-reply-to*: <20111002030248.B21738C0132@voluntocracy.org>*References*: <qotei0nf78i.fsf@ruuvi.it.helsinki.fi> <20110815160512.1C1008C0663@voluntocracy.org> <20110815190618.GB31780@mercury.ccil.org> <20111002021320.GB17057@mercury.ccil.org> <20111002030248.B21738C0132@voluntocracy.org>

Aubrey Jaffer scripsit: > | > That's reasonable: in fact, SCM doesn't support exact/exact > | > complex numbers either, which is perfectly fine. It just means > | > that no general complex number can be real. > > All real numbers are complex numbers. This derives from their > mathematical definitions. *General* complex number is a term defined in R5RS: it means non-real complex number, where "general" is used in the sense of "general case." Because it seems to confuse people, I have removed it from the draft R7RS. > Shouldn't the predicates REAL? and COMPLEX? implement the mathematical > semantics for which they are named? Inexact numbers don't obey mathematical semantics in any case: for example, inexact addition is not associative. There are two reasonable sets of semantics here, and by providing two sets of procedures we can support both. By adding an "exact-complex" feature, a program that depends on exact complex numbers can rely on being run only on an implementation that supports them. -- Almost all theorems are true, John Cowan <cowan@x> but almost all proofs have bugs. http://www.ccil.org/~cowan --Paul Pedersen _______________________________________________ Scheme-reports mailing list Scheme-reports@x http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports

**Follow-Ups**:**Re: [Scheme-reports] Numerical example (real? -2.5+0.0i)***From:*Aubrey Jaffer <agj@x>

**References**:**[Scheme-reports] Numerical example (real? -2.5+0.0i)***From:*Jussi Piitulainen <jpiitula@x>

**Re: [Scheme-reports] Numerical example (real? -2.5+0.0i)***From:*Aubrey Jaffer <agj@x>

**Re: [Scheme-reports] Numerical example (real? -2.5+0.0i)***From:*John Cowan <cowan@x>

**Re: [Scheme-reports] Numerical example (real? -2.5+0.0i)***From:*John Cowan <cowan@x>

**Re: [Scheme-reports] Numerical example (real? -2.5+0.0i)***From:*Aubrey Jaffer <agj@x>

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