[PPL-devel] floating point behaviour

[piotrm]

Apologies if this is not the right place to inquire about this, cannot  
seem to find any other outlet:

Is it correct behavior for floating point calculations to be done  
differently once ppl.hh is included in a c++ program as well as the  
printing of floats? Here is an example of what I'm referring to:

#include <cstdio>

int main() {
   double a = 0.50000000000000011102230246251565404236316680908203125;
   double b = 0.5f / a;
   printf("%0.60f %f %0.60f %f\n", a, a, b, b);
   return 0;
}

This prints (for me)

0.500000000000000111022302462515654042363166809082031250000000  
0.500000  
0.999999999999999777955395074968691915273666381835937500000000 1.000000

If I include ppl, as in below:

#include <cstdio>
#include "ppl.hh"

int main() {
   double a = 0.50000000000000011102230246251565404236316680908203125;
   double b = 0.5f / a;
   printf("%0.60f %f %0.60f %f\n", a, a, b, b);
   return 0;
}

I get the following

0.500000000000000111022302462515654042363166809082031250000000  
0.500000  
0.999999999999999888977697537484345957636833190917968750000000 0.:00000

Notice the strange way the b is printed the second time. I also found  
instances where numbers that are close to 0.01 get printed as 0.00:000

Is this perhaps an installation issue on my part? I noticed this using  
the OCaml interface, that is, use of ppl changed the behavior of the  
float types in OCaml in the same way the behavior is changed in C++  
above.