MATLAB: How to reshape a n x m matrix into n*m,1 matrix

Question

For example I have a matrix B with n=3,m=7

B =[ 0     0     0     0     0     0  -100;
     0     0     0     0     0     0  -100;
     0     0     0     0     0     0  -100;]

I want to reshape it to n*m,1 (21,1)

B = [0; 0; 0; 0; 0; 0; -100; 0; 0; 0; 0; 0; 0; -100; 0; 0; 0; 0; 0; 0; -100;];

I tried using reshape(B,21,1) or reshape(B,[],1) or reshape(B,[21,1]) but it converts it into

B = [0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; -100; -100; -100;];

Answer 1

reshape(B.',[],1)