[Insight-developers] vnl_math::pi coming up undefined with vector optimization turned on?

[kent williams]

I'm trying to build ITK on OS X with the "-O3" flag. I've never had trouble
with "-O2" but now I get an undefined external for vnl_math::pi.

The main reason to go with "-O3" is to turn on vector SIMD optimizations --
in one application we're trying to optimize, the biggest share of CPU is
used in the ImageToImageMetric, and Shark is suggesting that the loops in
the hot routines would benefit from vector optimizations.

I don't know why or from whence the problem originates, but what it looks
like is that the vnl_math:: constants don't get declared as variables if
VCL_STATIC_CONST_INIT_FLOAT_NO_DEFN is defined.

Now I'm no VXL library hacker,so I'm pretty much baffled by this thing.