Benchmark: running SparkyG, demerphq, integral2, intgrl2_f, intgrl_np, intgrl_pp, iterative, each for at least 1 CPU seconds...
   SparkyG:  1 wallclock secs ( 1.06 usr +  0.01 sys =  1.07 CPU) @ 1570.09/s (n=1680)
  demerphq:  1 wallclock secs ( 1.05 usr +  0.02 sys =  1.07 CPU) @ 2283.18/s (n=2443)
 integral2:  2 wallclock secs ( 1.10 usr +  0.02 sys =  1.12 CPU) @ 3428.57/s (n=3840)
 intgrl2_f:  2 wallclock secs ( 1.07 usr +  0.02 sys =  1.09 CPU) @ 2900.92/s (n=3162)
 intgrl_np:  2 wallclock secs ( 1.08 usr +  0.00 sys =  1.08 CPU) @ 3110.19/s (n=3359)
 intgrl_pp:  1 wallclock secs ( 1.05 usr +  0.00 sys =  1.05 CPU) @ 3199.05/s (n=3359)
 iterative:  1 wallclock secs ( 1.04 usr +  0.01 sys =  1.05 CPU) @ 4265.71/s (n=4479)
            Rate SparkyG demerphq intgrl2_f intgrl_np intgrl_pp integral2 iterative
SparkyG   1570/s      --     -31%      -46%      -50%      -51%      -54%      -63%
demerphq  2283/s     45%       --      -21%      -27%      -29%      -33%      -46%
intgrl2_f 2901/s     85%      27%        --       -7%       -9%      -15%      -32%
intgrl_np 3110/s     98%      36%        7%        --       -3%       -9%      -27%
intgrl_pp 3199/s    104%      40%       10%        3%        --       -7%      -25%
integral2 3429/s    118%      50%       18%       10%        7%        --      -20%
iterative 4266/s    172%      87%       47%       37%       33%       24%        --