[bug-gawk] Interesting floating point behavior

[Robert Kennedy]

# gawk --version
GNU Awk 4.0.0

# echo -e "Input\t*10000\t%100"; for i in 0.67 0.68 0.69 0.70; do echo
$i |gawk '{a=$1; b=a*10000; c=b%100; print a,"\t",b,"\t",c}'; done

Input   *10000  %100
0.67     6700    0
0.68     6800    9.09495e-13
0.69     6900    100
0.70     7000    0

The very-close-to-zero number for 0.68 is not surprising, the result
of the modulo for the 0.69 input seems... strange. You can see this
happen at .57 as well:

echo -e "Input\t*10000\t%100"; for i in $(seq -w 00 99); do echo
"0.$i" |gawk '{a=$1; b=a*10000; c=b%100; print a,"\t",b,"\t",c}'; done

This has been around since the 3.1 days at least.  Any ideas?

Cheers,
Robert K.

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