diff_ang2h, diff_ang2k, diff_ang2l, diff_ang2psi

diff_ang2h( $tt, $om, $ch, $ph)
diff_ang2h( $mu, $om, $ch, $ph, $ga, $de)
diff_ang2k( $tt, $om, $ch, $ph)
diff_ang2k( $mu, $om, $ch, $ph, $ga, $de)
diff_ang2l( $tt, $om, $ch, $ph)
diff_ang2l( $mu, $om, $ch, $ph, $ga, $de)
diff_ang2psi( $tt, $om, $ch, $ph)
diff_ang2psi( $mu, $om, $ch, $ph, $ga, $de)

Returns a calculated component of the q-vector, including psi, that correspond to the specified set of angles.
$h = diff_ang2h( -1, 46, -97, 126);