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I’ve updated the problem statement for #13 per posting on Mainframe Assembler List indicating it was incorrect.  I’ve also posted a new solution to #13 using 7 DFP instructions to perform the required division and rounding to 2 decimal places.  Calculating the number of significant digits to request for rounding to 2 decimal places was not exactly trivial since the division produced an irrational fraction with repeating sequence of 270270… which resulted in 16 significant digit result with corresponding exponent set to required position versus preferred position.  Visit the web site to see source and log listings:

http://z390.sourceforge.net/z390_Mainframe_Assemble_Coding_Contest.htm

Note running this solution on z390 requires update to PTF level v1400a which can now be downloaded in InstallShield format for easy installation from www.z390.org.  This PTF fixes trap in RRDTR and RRXTR under some conditions and includes trailing zeros as significant digits in ESDTR and ESXTR instructions.  Also the traces for several DFP instructions have been corrected to show correct GPR versus FPR registers.

Although figuring out how to do this in DFP was fun, I don’t recommend changing existing PD routines like Steve’s P13SC1.MLC unless there is a well defined business application requirement such as the need for an industry standard method that can be used on different hardware and software platforms producing exactly the same result.

Don Higgins

mailto:don@...

http://don.higgins.net