94e-01 f-delta = 1.3e-03
 Iter 55: f = 9.661493e-01 f-delta = 1.2e-03
 Iter 56: f = 9.672469e-01 f-delta = 1.1e-03
 Iter 57: f = 9.682348e-01 f-delta = 9.9e-04
 Iter 58: f = 9.691174e-01 f-delta = 8.8e-04
 Iter 59: f = 9.699007e-01 f-delta = 7.8e-04
 Iter 60: f = 9.705915e-01 f-delta = 6.9e-04
 Iter 61: f = 9.711975e-01 f-delta = 6.1e-04
 Iter 62: f = 9.717263e-01 f-delta = 5.3e-04
 Iter 63: f = 9.721858e-01 f-delta = 4.6e-04
 Iter 64: f = 9.725836e-01 f-delta = 4.0e-04
 Iter 65: f = 9.729269e-01 f-delta = 