Extracting a Dirac column vector from a Dirac propagator matrix

Syntax	void QLA_D_eqop_diracvec_P( restrict QLA_DiracFermion *r,
	QLA_DiracPropagator *a, int jc, int js)
Meaning	$r_{i_c,i_s} = a_{i_c,i_s,j_c,j_s}\ \ \ \mbox{for $i_c = 0\ldots{}n_c-1, i_s = 0\ldots{}3$}$
eqop	eq