[Flightgear-devel] Template questions

[Jon Berndt]

I've got a problem with an undefined reference. I've set up a function
template in one of my classes. The declaration is:

template <class T>
  T IntegrateAB4(double delta_t, T& vLast, T* vLastArray);

The definition is:

template <class T>
   T FGState::IntegrateAB4(double delta_t, T& vLast, T *vLastArray)
{
    T vResult;

    // Fourth order Adams-Bashforth integrator
    vResult = (delta_t/24.0)*(  55.0 * vLast
                              - 59.0 * vLastArray[0]
                              + 37.0 * vLastArray[1]
                              -  9.0 * vLastArray[2] );

    vLastArray[2] = vLastArray[1];
    vLastArray[1] = vLastArray[0];
    vLastArray[0] = vLast;

    return vResult;
}

I try and call this function from another class like this:

    vUVW += State->IntegrateAB4(Tc, vUVWdot, vUVWdot_prev);

Everything compiles, but I get this error:

FGTranslation.o::FGTranslation.cpp: undefined reference to
`FGColumnVector3 FGState::IntegrateAB4<FGColumnVector3>(double,
FGColumnVector3 &, FGColumnVector3 *)'

I may abandon this approach, but I'd at least like to understand what the
problem is. I've got a hunch, but it's incomplete. :-)

Comments?

Jon

smime.p7s
Description: application/pkcs7-signature