int nside = 2;
int ipring = (int) pt.nest2ring(nside, ipnest);
assertEquals("ipring=" + ipring, 0, ipring, 1e-10);
ipnest = 0;
nside = 2;
ipring = (int) pt.nest2ring(nside, ipnest);
assertEquals("ipring=" + ipring, 13, ipring, 1e-10);
ipnest = 18;
nside = 2;
ipring = (int) pt.nest2ring(nside, ipnest);
assertEquals("ipring=" + ipring, 27, ipring, 1e-10);