Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

QVM: Quaternions, Vectors, Matrices

BOOST_QVM_INLINE_OPERATIONS

#include <boost/qvm/inline.hpp>

#ifndef BOOST_QVM_INLINE_OPERATIONS
#define BOOST_QVM_INLINE_OPERATIONS BOOST_QVM_INLINE
#endif

Boost QVM uses BOOST_QVM_INLINE_OPERATIONS in definitions of functions that implement various high-level operations, such as matrix multiplication, computing the magnitude of a vector, etc.