Next: FORTRAN version Up: Floating point precision Previous: Floating point precision

C version


Lest this program stop prematurely, i.e. before displaying

    `END OF TEST',

try to persuade the computer NOT to terminate execution when an
error like Over/Underflow or Division by Zero occurs, but rather
to persevere with a surrogate value after, perhaps, displaying some
warning.  If persuasion avails naught, don't despair but run this
program anyway to see how many milestones it passes, and then
amend it to make further progress.

Answer questions with Y, y, N or n (unless otherwise indicated).


To continue, press RETURN
Diagnosis resumes after milestone Number 0          Page: 1

Users are invited to help debug and augment this program so it will
cope with unanticipated and newly uncovered arithmetic pathologies.

Please send suggestions and interesting results to
        Richard Karpinski
        Computer Center U-76
        University of California
        San Francisco, CA 94143-0704, USA

In doing so, please include the following information:
        Precision:      double;
        Version:        10 February 1989;
        Computer:

        Compiler:

        Optimization level:

        Other relevant compiler options:

To continue, press RETURN
Diagnosis resumes after milestone Number 1          Page: 2

Running this program should reveal these characteristics:
     Radix = 1, 2, 4, 8, 10, 16, 100, 256 ...
     Precision = number of significant digits carried.
     U2 = Radix/Radix^Precision = One Ulp
        (OneUlpnit in the Last Place) of 1.000xxx .
     U1 = 1/Radix^Precision = One Ulp of numbers a little less than 1.0 .
     Adequacy of guard digits for Mult., Div. and Subt.
     Whether arithmetic is chopped, correctly rounded, or something else
        for Mult., Div., Add/Subt. and Sqrt.
     Whether a Sticky Bit used correctly for rounding.
     UnderflowThreshold = an underflow threshold.
     E0 and PseudoZero tell whether underflow is abrupt, gradual, or fuzzy.
     V = an overflow threshold, roughly.
     V0  tells, roughly, whether  Infinity  is represented.
     Comparisions are checked for consistency with subtraction
        and for contamination with pseudo-zeros.
     Sqrt is tested.  Y^X is not tested.
     Extra-precise subexpressions are revealed but NOT YET tested.
     Decimal-Binary conversion is NOT YET tested for accuracy.

To continue, press RETURN


peter@physik3.gwdg.de
Tue Aug 8 13:05:00 GMT+0200 1995