reshape is a great way to do this:
x=rand(100000,1);
y=reshape(x,1000,100);
y1=reshape(x,1000,[]); % Because the 100 is determined, you can let MATLAB calculate it
y2=reshape(x,[],100); % Because the 1000 is determined, you can let MATLAB calculate it
x(1:10)
x(1001:1010)
y(1:10,1:2)
