On Sun, 27 Apr 2008 12:11:49 -0400 "John P. Baker" <[EMAIL PROTECTED]> wrote:
:> 1. How are we to distinguish between a binary floating-point literal, a :>decimal floating-point literal, and a hexadecimal floating-point literal? What is a binary floating point literal? Or a hexadecimal floating point literal? They would tend to be simple data not converted by the compiler. :> 2. How are we to distinguish between a four-byte floating-point literal, :>an eight-byte floating-point literal, and a sixteen-byte floating-point :>literal? Typically E is used for short, D is used for long and L is now being used for double long. :>Some examples I have seen use various letter suffixes to indicate length and :>format. But is there a standard? Should be. 1.5E+0 - short. 1.5D+0 - long. 1.5L+0 - double long. What are you trying to do? Determine an interchange format? :>-----Original Message----- :>From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf :>Of Don Higgins :>Sent: Sunday, April 27, 2008 8:41 AM :>To: [email protected] :>Subject: Re: Fixed-Point and Scientific Notation :> :>John, all :> :>Here are some references and summary info I've collected: :> :>Standard Scientific Notation: :> General description and references: :> http://en.wikipedia.org/wiki/Scientific_notation :> IBM Hursley generalized description of scientific notation conversion: :> http://www2.hursley.ibm.com/decimal/daconvs.html#reftonum :> Arithmetic Model: :> http://www2.hursley.ibm.com/decimal/damodel.html :> :>Note this model is based on IEEE 854, ANSI X3-274 standards. :>Unfortunately these standards are only available in published form for a :>fee. (Commentary: It would be a tremendous service to the world if a :>non-profit organization could be started to move all standards :>publications to the public domain to help promote understanding and use of :>non-proprietary standards. Charging for them makes them all proprietary!) :> :>So in summary the standard form would appear to be: :> :> 1. Sign (+optional) :> :> 2. Mantissa (decimal digits with optional period up to maximum :>significant digits for binary format) :> :> 3. Exponent (optional) :> a. E (E or e optional if sign included) :> b. Sign (+optional if E or e) :> c. Power of ten (exponent digits with no decimal up to maximum :>exponent) :> :>The maximum limits for each IBM fixed and floating point HFP, BFP, and DFP :>format can be found in the latest Principles of Operations Manual here: :> :>http://publibfp.boulder.ibm.com/epubs/pdf/dz9zr006.pdf :> :>In summary the significant decimal digits and base 10 exponents are as :>follows: :> :> Summary of IBM Fixed and Floating Point Scientific Notation Limits :> Type of number 32 bit 64 bit 128 bit :> :> Fixed Point Integers :> Significant digits 10 19 39 :> :> HFP Hexadecimal FP :> Significant digits 7 15 34 :> Maximum exponent 75 75 75 :> :> :> BFP Binary IEEE 754 FP :> Significant digits 7 16 34 :> Maximum exponent 38 308 4932 :> :> DFP Decimal IEEE 754r FP :> Significant digits 7 16 34 :> Maximum exponent 96 384 6144 :> :>All of these formats are supported by z390 on Windows and Linux with CTD :>and CFD conversion routine macros and supervisor calls for converting :>between EBCDIC/ASCII character scientific notation and any of the above :>binary formats. All corrections and comments welcome. -- Binyamin Dissen <[EMAIL PROTECTED]> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel Should you use the mailblocks package and expect a response from me, you should preauthorize the dissensoftware.com domain. I very rarely bother responding to challenge/response systems, especially those from irresponsible companies. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
