c++ - how do I make a portable isnan/isinf function

Question

I've been using isinf, isnan functions on Linux platforms which worked perfectly. But this didn't work on OS-X, so I decided to use std::isinf std::isnan which works on both Linux and OS-X.

But the Intel compiler doesn't recognize it, and I guess its a bug in the intel compiler according to http://software.intel.com/en-us/forums/showthread.php?t=64188

So now I just want to avoid the hassle and define my own isinf, isnan implementation.

Does anyone know how this could be done?

edit:

I ended up doing this in my source code for making isinf/isnan working

#include <iostream>
#include <cmath>

#ifdef __INTEL_COMPILER
#include <mathimf.h>
#endif

int isnan_local(double x) { 
#ifdef __INTEL_COMPILER
  return isnan(x);
#else
  return std::isnan(x);
#endif
}

int isinf_local(double x) { 
#ifdef __INTEL_COMPILER
  return isinf(x);
#else
  return std::isinf(x);
#endif
}


int myChk(double a){
  std::cerr<<"val is: "<<a <<"";
  if(isnan_local(a))
    std::cerr<<"program says isnan";
  if(isinf_local(a))
    std::cerr<<"program says isinf";
  std::cerr<<"
";
  return 0;
}

int main(){
  double a = 0;
  myChk(a);
  myChk(log(a));
  myChk(-log(a));
  myChk(0/log(a));
  myChk(log(a)/log(a));

  return 0;
}

Answer 1

You could also use boost for this task:

#include <boost/math/special_functions/fpclassify.hpp> // isnan

if( boost::math::isnan( ... ) .... )