MATLAB: Element-wise creation of Matrix

MATLABmatrix manipulation

How can we create element wise matrix from 4 matrices without using loops. For ex.we have

A=[a1 a2;a3 a4] B=[b1 b2;b3 b4] C=[c1 c2;c3 c4] D=[d1 d2;d3 d4]

We need to create an array such that each array location contains values such as

R=[a1 b1;c1 d1] %Matrix on First location

S=[a2 b2;c2 d2] %Matrix on Second location

and so on so that all the elements are covered.

Thanks in advance.

idx = 1;
R = [A(idx), B(idx); C(idx), D(idx)]

idx = isnan(b);
c = a(idx);
D = [a(~idx), b(~idx)];

C=reshape([a b c].',[],1);