For a fraction,
\fp_eval:n { 1/9000000000000000 } > 0.0000000000000001111111111111111
displays the 16 significant digits after a long run of zeros. In that
spirit I find it disconcerting that for sin(pi)
\fp_eval:n { sin(pi) } > 0.0000000000000002384626433832795
as if the 16 nonzero digits after the run of zeros are the significant
ones. They are actually the 16 significant figures of \fp_eval:n {sin(pi
 0.0000000000000001)}, and "noise" as far as sin(pi) is concerned. For
cos(pi/2)
\fp_eval:n { cos(pi/2) } > 0.0000000000000006192313216916398
The 16 apparently significant figures are those from \fp_eval:n {
cos(pi/2  .0000000000000001) }
Rounding the cosine to 16 figures gives a 6 in the last place, which
seems large to me. Perhaps sin and cos and their fellows should be given
the exact value 0 at the appropriate multiples of pi/2?
Andrew Parsloe
