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

*To*: scheme-reports@x*Subject*: Re: [Scheme-reports] (angle -0.0-0.0i) should be -pi, but R7RS-draft-6 prohibits this*From*: Mark H Weaver <mhw@x>*Date*: Tue, 07 Aug 2012 16:11:32 -0400*In-reply-to*: <50217290.10401@netris.org>*References*: <50217290.10401@netris.org>

On 08/07/2012 03:54 PM, Mark H Weaver wrote: > There is widespread agreement in the relevant floating point standards > (C99, C11, ISO/IEC 10967, and probably IEEE 754 although I haven't > purchased a copy) that (angle -0.0-0.0i) = (atan -0.0 -0.0) = -pi, but > the definition of 'angle' on page 36 of R7RS-draft-6 (section 6.2.6) > asserts that -pi< (angle z)<= pi for all complex 'z'. I suggest that > this be changed to -pi<= (angle z)<= pi. Another problem along the same lines: earlier on page 36, R7RS-draft-6 asserts that the value of "log z is defined to be the one whose imaginary part lies in the range from -pi (exclusive) to pi (inclusive)", and then proceeds to define the inverse trigonometric functions in terms of log. That should be changed to '-pi (inclusive)'. Note that X3J13 voted for these changes to Common Lisp in January 1989. Search for "COMPLEX-ATAN-BRANCH-CUT" in the following pages for more details: http://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node128.html http://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node129.html Mark _______________________________________________ Scheme-reports mailing list Scheme-reports@x http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports

**Follow-Ups**:**Re: [Scheme-reports] (angle -0.0-0.0i) should be -pi, but R7RS-draft-6 prohibits this***From:*Alex Shinn <alexshinn@x>

**Re: [Scheme-reports] (angle -0.0-0.0i) should be -pi, but R7RS-draft-6 prohibits this***From:*Vassil Nikolov <vnikolov@x>

**Re: [Scheme-reports] (angle -0.0-0.0i) should be -pi, but R7RS-draft-6 prohibits this***From:*John Cowan <cowan@x>

**References**:**[Scheme-reports] (angle -0.0-0.0i) should be -pi, but R7RS-draft-6 prohibits this***From:*Mark H Weaver <mhw@x>

- Prev by Date:
**[Scheme-reports] (angle -0.0-0.0i) should be -pi, but R7RS-draft-6 prohibits this** - Next by Date:
**Re: [Scheme-reports] (angle -0.0-0.0i) should be -pi, but R7RS-draft-6 prohibits this** - Previous by thread:
**[Scheme-reports] (angle -0.0-0.0i) should be -pi, but R7RS-draft-6 prohibits this** - Next by thread:
**Re: [Scheme-reports] (angle -0.0-0.0i) should be -pi, but R7RS-draft-6 prohibits this** - Index(es):