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*To*: Mark H Weaver <mhw@x>*Subject*: Re: [Scheme-reports] (angle -0.0-0.0i) should be -pi, but R7RS-draft-6 prohibits this*From*: Alex Shinn <alexshinn@x>*Date*: Wed, 8 Aug 2012 09:39:51 +0900*Cc*: scheme-reports@x*In-reply-to*: <50217674.50804@netris.org>*References*: <50217290.10401@netris.org> <50217674.50804@netris.org>

On Wed, Aug 8, 2012 at 5:11 AM, Mark H Weaver <mhw@x> wrote: > 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 Thanks Mark. We'll review these. -- Alex _______________________________________________ Scheme-reports mailing list Scheme-reports@x http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports

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

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

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