A Prediction Model of Forest Preliminary Precision Fertilization Based on Improved GRA-PSO-BP Neural Network

Table 4

Grey correlation degree and grey correlation coefficient of each influencing factor and output fertilization amount.

XNi	εoi	roi		εoi	roi		εoi	roi
X1	εo1 = (0.9178,…,0.8813)	0.9105	X1	εo1 = (0.9512,…,0.8731)	0.9334	X1	εo1 = (0.7483,…,0.4639)	0.7512
X2	εo2 = (0.9259,…,0.8947)	0.9122	X2	εo2 = (0.9554,…,0.8793)	0.9357	X2	εo2 = (0.7644,…,0.4744)	0.7559
X3	εo3 = (0.8972,…,0.9323)	0.9115	X3	εo3 = (0.9372,…,0.9191)	0.9441	X3	εo3 = (0.7312,…,0.6561)	0.7606
X4	εo4 = (0.9240,…,0.9390)	0.9232	X4	εo4 = (0.9544,…,0.8992)	0.9398	X4	εo4 = (0.7605,…,0.5119)	0.7715
X5	εo5 = (0.9338,…,0.9554)	0.9009	X5	εo5 = (0.9594,…,0.9063)	0.9321	X5	εo5 = (0.7800,…,0.5262)	0.7372
X6	εo6 = (0.9194,…,0.9516)	0.9119	X6	εo6 = (0.9520,…,0.9046)	0.9368	X6	εo6 = (0.7514,…,0.5229)	0.7561
X7	εo7 = (0.6660,…,0.6646)	0.6142	X7	εo7 = (0.6016,…,0.6144)	0.6736	X7	εo7 = (0.3952,…,0.3762)	0.5868