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)
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?