intersect
intersect(bchans, btxpow, &nb, gchans, gtxpow, ng);
intersect(tchans, ttxpow, &nt, achans, atxpow, na);
intersect(tgchans, tgtxpow, &ntg, gchans, gtxpow, ng);
intersect(gchans, gtxpow, &ng, nchans, ntxpow, nn);
intersect(achans, atxpow, &na, nchans, ntxpow, nn);