On 12/10/2015 02:55 PM, Mathieu Malaterre wrote: > Is there a way to test that for sure. A naive solution like: > > $ LD_PRELOAD=$HOME/libc.so.6 ./mycode > > results in > > relocation error: /home/mathieu/libc.so.6: symbol _dl_starting_up, > version GLIBC_PRIVATE not defined in file ld-linux-x86-64.so.2 with > link time reference Sure. Find the different result and test it. All you have to do is log all the calls to the standard functions and compare. It's unlikely to be std::ceil or std::sqrt. Andrew.