Re: modify coord-rotate to get exact values for (sin PI) etc (issue 269530043 by address@hidden)

[benko . pal]

sorry to chime in that late, but:
am I right that the problem is that we get the rotation matrix
cos a   -sin a
sin a    cos a
inexact?  and if so, how the inexactness is present?  one of the
diagonals is exactly +/-1 while the other is not exactly 0?
in that case I'd suggest (would have suggested) to perform a paranoid
normalization of the (cos a, sin a) vector, which e.g. normalizes (1,
1e-9) into (1, 0).


https://codereview.appspot.com/269530043/