er 43: f = 9.456825e-01 f-delta = 2.0e-03
 Iter 44: f = 9.477010e-01 f-delta = 2.0e-03
 Iter 45: f = 9.496999e-01 f-delta = 2.0e-03
 Iter 46: f = 9.516689e-01 f-delta = 2.0e-03
 Iter 47: f = 9.535964e-01 f-delta = 1.9e-03
 Iter 48: f = 9.554701e-01 f-delta = 1.9e-03
 Iter 49: f = 9.572772e-01 f-delta = 1.8e-03
 Iter 50: f = 9.590055e-01 f-delta = 1.7e-03
 Iter 51: f = 9.606440e-01 f-delta = 1.6e-03
 Iter 52: f = 9.621834e-01 f-delta = 1.5e-03
 Iter 53: f = 9.636167e-01 f-delta = 1.4e-03
 Iter 54: f = 9.6493