Quadruple Precision in C++ (GCC)

c++, floating-point, gcc, quadruple-precision

Solution

Apparently, this seems to have been an installation error on my part.

While the core C/C++ portion of the GCC includes libquadmath.so, the Fortran version supplies libquadmath.a and quadmath.h, which can be included to access the functions.

#include <quadmath.h>
#include <iostream>
int main()
{
  char* y = new char[1000];
  quadmath_snprintf(y, 1000, "%Qf", 1.0q);
  std::cout << y << std::endl;
  return 0;
}

Problem

Just recently, the GCC 4.6.0 came out along with libquadmath. Unfortunately, GNU has supported Fortran, but not C or C++ (all that is included is a .so). I have not found a way to use these new features in C++, however, GNU C does support the `__float128` type for guaranteed quadruple-precision floats. GNU C does not seem to support the math functions in libquadmath, such `fabsq` (absolute value, `q` being the suffix for quad). Is there any way to get these functions working in C++, or is there some alternative library that I could use for math functions with `__float128`? What is the best method for getting quadruple-precision floats working in the GCC? Right now, I can add, subtract, and multiply them, but this is useless to me, considering how I have no way to convert them to strings or use functions such as `truncq` and `fabsq` to create my own string function.

Original source