clc
clear all
% in class exercies - post test 2
disp('How to use vectors - Chapter 26')
% Exercise 3
% find the dot product
disp('Exercise 3')
disp('Find the dot product of two equal sized vectors')
% input both vectors
v1=[3 -7 23];
v2=[-7 0 12];
disp('  The first vector is:')
disp(v1)
disp('  The second vector is:')
disp(v2)
% code
% check vector sizes
n1=length(v1);
n2=length(v2);
if n1==n2
    sump=0;
    for i=1:1:n1
        sump=sump+v1(i)*v2(i);
    end
else
    disp('Error - Vectors are not the same size')
end
fprintf('  The vector dot product is %g\n\n',sump)
% Exercise 4
% Young's modulus
disp('Exercise 4')
disp('Find the young''s modulus of a material')
disp(' ')
% inputs
strain=[0.00010 0.00012 0.0010 0.0015 0.0018 0.0022 0.0026];
stress=[19.1 22.81 187 284.2 344.3 417.0 495.0]; % MPa
% displaying inputs
n=length(stress);
disp('  Input data:')
for j=1:1:n
    fprintf('  Strain = %5.4g, Stress = %4.3g MPa\n',strain(j),stress(j))
end
% code
top=0;
bot=0;
for i=1:1:n
    top=top+stress(i)*strain(i);
    bot=bot+strain(i)^2;
end
young=top/bot;
disp(' ')
fprintf('  The young''s modulus is %g GPa\n\n',young*10^(-3))