er 17: f = 8.422694e-01 f-delta = 4.8e-03
 Iter 18: f = 8.458255e-01 f-delta = 3.6e-03
 Iter 19: f = 8.488925e-01 f-delta = 3.1e-03
 Iter 20: f = 8.518580e-01 f-delta = 3.0e-03
 Iter 21: f = 8.549459e-01 f-delta = 3.1e-03
 Iter 22: f = 8.583117e-01 f-delta = 3.4e-03
 Iter 23: f = 8.620862e-01 f-delta = 3.8e-03
 Iter 24: f = 8.663939e-01 f-delta = 4.3e-03
 Iter 25: f = 8.713540e-01 f-delta = 5.0e-03
 Iter 26: f = 8.770652e-01 f-delta = 5.7e-03
 Iter 27: f = 8.835659e-01 f-delta = 6.5e-03
 Iter 28: f = 8.9076