because different tests have different ideas about what it means to be
"close enough" to the right answer, depending on the properties of the
function being tested. In the process, I fixed some warnings and
added a few more 'volatile' hacks, which are sufficient to make all
the tests pass at -O2 with clang.
result depend on the cosine and sine of the imaginary part.
Small values are used in the new tests such that cosine and sine are well
defined.
Reviewed by: das
