Don, I appreciate the information.
However, the clarifications I really need are: 1. How are we to distinguish between a binary floating-point literal, a decimal floating-point literal, and a hexadecimal floating-point literal? 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? Some examples I have seen use various letter suffixes to indicate length and format. But is there a standard? John P. Baker -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Don Higgins Sent: Sunday, April 27, 2008 8:41 AM To: IBM-MAIN@BAMA.UA.EDU 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. Don Higgins [EMAIL PROTECTED] www.z390.org ---------------------------------------------------------------------- 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