With neural networks, we are working with sets of matrices:
In order to use optimizing functions such as "fminunc()", we will want to "unroll" all the elements and put them into one long vector:
If the dimensions of Theta1 is 10x11, Theta2 is 10x11 and Theta3 is 1x11, then we can get back our original matrices from the "unrolled" versions as follows:
To summarize:
來(lái)源：coursera 斯坦福 吳恩達(dá) 機(jī)器學(xué)習(xí)
