It is trying to use a dvar_matrix constructor to print out the object.
The constructor is declared in the header fvar.hpp, but I guess never
implemented. Probably do it yourself with something like
init_bounded_vector_vector dFt(1,nsp,1,nFt,-5,5,phase);
matrix M(1,nsp)
LOC_CALCS
for (int i=1;i<=n;i++)
{
M(i)=dFt(i);
}
and use M in your code.