How can I solve this problem using for loop?

for the given vector [2 2 5 8], without using sum() and diff() how can i perform 2*2 + 2*5 + 5*8 = 54. Using for loop. here the consicutive number are multiplied and then addition is performed.

Answer 1

[Matt J]

v=[2 2 5 8];

for i=1
 result=v(1:end-1)*v(2:end).'    
end

result = 54

[DGM]

Oof. I missed the requirement to have a superfluous loop. I guess I flunked that test.

[Manav Divekar]

Sorry this is not working

[DGM]

You'll have to describe how it's not working for you.

[Manav Divekar]

function [out] = pairprodsum (m)
s = 0
for i = 1
	b = m(1:end-1).*m(2:end);
	s = s + b;
end
out = s;

If i use it in this i am just able to get the multiplied array, i am trying to get the sum also

[Matt J]

That's not what I proposed. I had

b = m(1:end-1)*m(2:end).';

[Manav Divekar]

this is giving a matrix, not the summation.

[Matt J]

I demonstrated to you in my original answer that it does give the summation. This is assuming the vector is a row vector, which it was in your original post.

Answer 2

[Emmanuel]

total = 0;

x = [2,2,5,8];

n = length(x);

for i =1:n-1

total = total + x(i)*x(i+1);

end

disp(total)