[discussing -ffast-math]
<rac> "This option should never be turned on by
 any -O option since it can result in incorrect output for programs which
 depend on an exact implementation of IEEE or ISO rules/specifications
 for math functions. "
<rac> i've said it before, and i'll say it again
 ... i see no use in a computer giving me the wrong answer very rapidly,
 i can do that myself
