The Prediction of Metro Shield Construction Cost Based on a Backpropagation Neural Network Improved by Quantum Particle Swarm Optimization

Table 3

Optimization calculation process of the QPSO.

Iteration (n)	Fitness (n − 1)	Fitness (n)	Fitness (n) − Fitness (n − 1)	Result
147	2.388799	2.388799	0 < 0.00001	Continue
148	2.388799	2.388807	0.000008 < 0.0001	Continue
149	2.388807	2.388807	0 < 0.0001	Continue
1000	2.388807	2.388807	0 < 0.0001	Stop