Page 228 - Compact Numerical Methods For Computers

Minimising a nonlinear sum of squares 217
numerical approximation of the Jacobian as in §18.2 gives, from the same
starting point,
T
b*=(196·251,49·1012,-0·313692)
with S(b*)=2·6113 in 7 iterations and 16 function evaluations. By comparison, if
the starting point is
(0) T (0)
b =(1, 1, 1) S(b )=24349·5
then using analytic derivatives yields
T
b*=(196·151,49·0876,-0·313589)
with S(b*)=2·58726 in 19 iterations and 33 evaluations, while numerically
approximated derivatives give
T
b*=(194·503,48·8935,-0·314545)
with S(b*)=2·59579 in 20 iterations and 36 evaluations.