[pgrouting-users] importance of -frounding-math compilation flag?

Stephen Woodbridge woodbri at swoodbridge.com
Sat Mar 16 16:47:10 PDT 2013

On 3/16/2013 6:20 PM, William Kyngesburye wrote:
> I'm recompiling pgrouting on OS X Lion, using the clang compiler.
> clang does not have the -frounding-math option.
> I found one reference that the clang equivalent is --disable-fpmath,
> but that just causes and error "unsupported option
> '--disable-fpmath'".  I could find no documentation that clang has or
> had this option, or something similar.
> Is the rounding behavior critical?

I do not know for a fact one way or the other, But I'm guess that this 
options probably is not critical for MOST pgrouting functions.

Where it MIGHT be important is for the CGAL library and/or GAUL 
libraries. CGAL specifically does a lot of math. You might check those 
packages so see what they do with respect to fp rounding on OS X.

If anyone knows more about this please correct this AND we should 
document it somewhere for future reference.


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