[R] Result differences in 32-bit vs. 64-bit point.in.polygon?

[Duncan Murdoch]

On 29/05/2015 2:36 PM, Lensing, Shelly Y wrote:
> Is anyone aware of point.in.polygon giving different results for 32-bit vs. 64-bit R? Our OS is 64-bit Windows 7 Enterprise. I'm working with someone else's extensive R program and the final results are close but not exactly matching. We're thinking it might be something with the point.in.polygon function (one of many possibilities, including leaps).

Often 32 bit R does calculations slightly more accurately than 64 bit R
does.  This is because the 64 bit compiler is more likely to do
calculations in 64 bit precision when the 32 bit compiler does them in
80 bit precision.  Of course, individual calculations being more
accurate doesn't mean the final answer is, but small numeric differences
in floating point calculations are to be expected.

Duncan Murdoch