Where is "m_quatF_set_matF" located in the source?

In the file mQuat.cc there is a function called SetMatrix.
Here's the function,

MatrixF * QuatF::setMatrix( MatrixF * mat ) const
{
   if( x*x + y*y + z*z < 10E-20f) // isIdentity() -- substituted code a little more stringent but a lot faster
      mat->identity();
   else
      m_quatF_set_matF( x, y, z, w, *mat );
   return mat;
}

The problem I'm having is that I cannot find m_quatF_set_matF() anywhere. The quat file only includes two files yet neither of them contains the function. I really need to find this as I'm doing a little demo engine of my own(Nothing commercial) but can't get quats converted into matrices properly. I was hoping this function could show me where I'm going wrong.