N(2,kept,const): random search 3000 vectors: min log-odds slope 0.7153 (12s)
   40 Nelder-Mead runs: min log-odds slope 0.7143 at log10(a,delta,c1,c2,c3,don,doff) = [ 6.   -0.56  6.   -6.   -6.    6.    2.32]
N(3,kept,const): random search 3000 vectors: min log-odds slope 0.7048 (17s)
   40 Nelder-Mead runs: min log-odds slope 0.7045 at log10(a,delta,c1,c2,c3,don,doff) = [-0.44 -0.72  6.   -6.   -6.    6.    0.07]
