Double and Float based fundamental types (vectors, matrices, etc.) implemented side by side?

Hi,

As I'm sure is standard practice, I have written a library to implement types like vectors, matrices, and so on, and it all works quite nicely. However I have hit a hurdle.

Using D3D9 for graphics, that seems to like having it's data in the form of single precision floats. Which is fair enough. But I'm feeling the need to do some intense physics simulation using double precision. So what I really want is some means of implementing both without duplicating my entire library.

My current implementation lets me switch between Float and Double types before compiling by means of a typedef instruction. But this doesn't quite give me the solution I need, as I'm stuck choosing one over the other.

[source lang="cpp"]// The library is called Util. Not a great name, I know. Here's a small excerpt
// from Util.h. Define DOUBLE before compiling to use the double type.
// Otherwise, use the float type.

#ifdef DOUBLE
typedef double Real;
#define NAMESPACE Maths::Double
#else
typedef float Real;
#define NAMESPACE Maths
#endif

namespace Util {
namespace NAMESPACE {
struct Angle; // Euler angle
struct Matrix; // 4x4 Matrix
struct Quaternion;
struct Vector3;
}
}

// An excerpt from Vector3.h

namespace util {
namespace NAMESPACE {
// Vector3, 3D coordinates
struct Vector3 {
public:
Real x, y, z;

Vector3(); // x=0 y=0 z=0
Vector3(Real); // x=a y=a z=a
Vector3(Real, Real, Real); // x=a y=b z=c
/// ... Etc.
};
}[/source]

Can anyone recommend a means to implement both types into the same library? Preferably while duplicating as little source code as possible.

I'm using Visual C++ 2010 Express. Thanks