Probe

The probe is defined in PTC as:

  type probe
     real(dp) x(6)
     type(spinor) s(3)
     type(rf_phasor) ac
     logical u
     type(integration_node),pointer :: lost_node
  end type probe

The probe has a real part x(6) which is simply a ray to be tracked through the lattice. The spinor consists of 3 spin axis. One can initialize a probe as follows:

 
   Probe=X

where X is an array of 6 real numbers. In that case, Probe%X=X. The spinor, which is a FPP construct containing a full basis, is initialized as the three indepedent spin axes, $\vec{i}$, $\vec{j}$ and $\vec{k}$.

The logical probe%u is set to true if the probe becomes unstable. probe%lost_node points to the place where the probe was lost. Finally probe%ac is used in modulating magnets in PTC and is described elsewhere.