Matrix, Dimensions.
implementation, you would have z^[1] equals w^[1] times x plus b^[1]. Where now z^[1] is obtained by taking the z^[1] for the individual examples. So there’s z^[1][1], z^[1][2] up to z^[1][m] and stacking them as follows and this gives you z^[1]. The dimension of z^[1] is that instead of being