Benchmark: timing 100000 iterations of mjd, new, original...
       mjd: 17 wallclock secs (16.86 usr +  0.00 sys = 16.86 CPU) @ 5931.20/s (n=100000)
       new:  3 wallclock secs ( 2.70 usr +  0.01 sys =  2.71 CPU) @ 36900.37/s (n=100000)
  original: 17 wallclock secs (12.87 usr +  0.01 sys = 12.88 CPU) @ 7763.98/s (n=100000)
            Rate      mjd original      new
mjd       5931/s       --     -24%     -84%
original  7764/s      31%       --     -79%
new      36900/s     522%     375%       --