I am getting error ".*" in vector multiplication

This is the code

clear; clc;

% Define element properties
E = 2e11; % Young's modulus
A = pi/4 * 1^2; % Cross-sectional area
L = 20; % Element length
I = pi/64 * 1^4; % Moment of inertia

% Define rotation matrix
theta = pi/2; % Rotation angle
R = [cos(theta) sin(theta) 0; -sin(theta) cos(theta) 0; 0 0 1];

% Define elemental stiffness matrix
Ke = [E*A/L 0 0 -E*A/L 0 0;
      0 12*E*I/L^3 6*E*I/L^2 0 -12*E*I/L^3 6*E*I/L^2;
      0 6*E*I/L^2 4*E*I/L 0 -6*E*I/L^2 2*E*I/L;
      -E*A/L 0 0 E*A/L 0 0;
      0 -12*E*I/L^3 -6*E*I/L^2 0 12*E*I/L^3 -6*E*I/L^2;
      0 6*E*I/L^2 2*E*I/L 0 -6*E*I/L^2 4*E*I/L];

% Assemble global stiffness matrix
K_global = zeros(18, 18);
% Element 1
K_global(1:6, 1:6) = K_global(1:6, 1:6) + R.' * Ke(1:6, 1:6) * R;
% Element 2
K_global([4 5 6 7 8 9], [4 5 6 7 8 9]) = K_global([4 5 6 7 8 9], [4 5 6 7 8 9]) + R.' * Ke([4 5 6 1 2 3], [4 5 6 1 2 3]) * R;
% Element 3
K_global([7 8 9 10 11 12], [7 8 9 10 11 12]) = K_global([7 8 9 10 11 12], [7 8 9 10 11 12]) + R.' * Ke([4 5 6 1 2 3], [4 5 6 1 2 3]) * R;
% Element 4
K_global([10 11 12 13 14 15], [10 11 12 13 14 15]) = K_global([10 11 12 13 14 15], [10 11 12 13 14 15]) + R.' * Ke([4 5 6 1 2 3], [4 5 6 1 2 3]) * R;
% Element 5
K_global([13 14 15 16 17 18], [13 14 15 16 17 18]) = K_global([13 14 15 16 17 18], [13 14 15 16 17 18]) + R.' * Ke([4 5 6 1 2 3], [4 5 6 1 2 3]) * R;

% Display global stiffness matrix
disp(K_global);

Error warning coming is

Error using *

Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the

number of rows in the second matrix. To operate on each element of the matrix individually, use TIMES (.*) for

elementwise multiplication.

Error in assignment2_Releaiblity (line 26)

K_global(1:6, 1:6) = K_global(1:6, 1:6) + R.' * Ke(1:6, 1:6) * R;

Answer 1

[Dyuman Joshi]

Ke(1:6,1:6) is 6x6 and R is 3x3. You can not multiply a 6x6 matrix with a 3x3 matrix.