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*To*: Moon at SCRC-TENEX, Common-Lisp at SU-AI*Subject*: floating-point format*From*: Robert A. Cassels <Cassels at SCRC-TENEX>*Date*: Thu, 16 Jun 1983 16:13:00 -0000*In-reply-to*: The message of 31 May 83 23:41-EDT from David A. Moon <Moon%SCRC-TENEX%MIT-MC at SU-DSN>

Date: Tuesday, 31 May 1983, 23:41-EDT From: David A. Moon <Moon%SCRC-TENEX%MIT-MC@SU-DSN> ... 16. Guy proposes the following treatment of floating point in FORMAT: ~w,d,pF ~w,d,x,pE ~w,d,pG The meanings of the arguments are exactly as for the FORTRAN-77 language as described in chapter 13 of the FORTRAN-77 standard, with the following exceptions and extensions: ... From ANSI X3.9 1978 (selected highlights from chapter 13) F editing: Optional blanks, optional sign, and a string of digits that contains a decimal point, rounded to d fractional digits. Leading zeros are not permitted except for an optional zero immediately to the left of the decimal point if the magnitude is less than one. The optional zero must appear if there would otherwise be no digits in the output field. [It says nothing about trailing zeros.] I guess we need to be specific about rounding. The spirit of Fortran, if not the letter, is that all digits printed are rounded in decimal. (Specified for F-format, but not for E-format.) Fortran rounding on ties is away from zero. (2.5 => 3, -2.5 => -3) IEEE says that binary-decimal conversions must respect the rounding mode, and the default rounding mode rounds to even on ties. Do we want to require that all digits printed be decimal-rounded for all formats? [I think so.] What rounding happens on ties? [I don't care -- either Fortran rounding or round-to-nearest-even is acceptable.]

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