matrix error, long answer

Pxx(1,1),Pxx(2,1) have right answer

but after 3, Pxx(3,1) it appear 0

I don't know why that answers are 0

I hope you can help me

Answer 1

[Chunru]

Becasue the range of data is too big, the displayed result using the default format may make the smaller value to be 0. Run the following command first before displaying Pxx.

format longg