How to make a global matrix

I am trying to make a global matrix out of these 4 matrices and then slim it down to the correct matrix for a stiffness problem.

close all
clear all
clc
E = 5.*10.^6;
v = .29;
A1 = 0.5;
A2 = 0.375;
A3 = 0.25;
A4 = 0.124;
%element 1
el1 = A1*E/30
a = [el1 0 -el1 0
    0 0 0 0
    -el1 0 el1 0
    0 0 0 0]
%element 2
el2 = A2*E/31.6228
l1 = 0.948711;
m1 = 0.316146;
b = el2.*[l1^2 l1*m1 -l1^2 -l1*m1
    l1*m1 m1^2 -l1*m1 -m1^2
    -l1^2 -l1*m1 l1^2 l1*m1
    -l1*m1 -m1^2 l1*m1 m1^2]
%element 3
el3 = A3*E/36.055
l2 = 0.832051;
m2 = 0.554699;
c = el3.*[l2^2 l2*m2 -l2^2 -l2*m2
    l2*m2 m2^2 -l2*m2 -m2^2
    -l2^2 -l2*m2 l2^2 l2*m2
    -l2*m2 -m2^2 l2*m2 m2^2]
%element 4
el4 = A4.*E./42.4264
l3 = 0.707107;
m3 = 0.707107;
d = el4*[l3^2 l3*m3 -l3^2 -l3*m3
    l3*m3 m3^2 -l3*m3 -m3^2
    -l3^2 -l3*m3 l3^2 l3*m3
    -l3*m3 -m3^2 l3*m3 m3^2]
%global system
 

[William Rose]

@Robert Fields, I'm not sure what you mean by "slim it down".

[Robert Fields]

By sliim it down I meant to a 4x4 or 6x6 matrix.

[William Rose]

@Robert Fields, you can create a 4x4 or 6x6 array and populate it with the elements you want from the 4x4x4 array.

e1=zeros(4,4); e2=zeros(6,6);

and so on. If all you really want is a 4x4 or 6x6 array made of selected elements of a, b, c, d, then I don't see the advantage of combing a,b,c,d into one 3D array. But I'm sure there's a reason...

Answer 1

[William Rose]

@Robert Fields,

%global system
e=cat(3,a,b,c,d); 
disp(size(e))

Try that.