what correction is required in the code?

I am trying to perform 2*2 + 2*5 + 5*8, for [2 2 5 8] vector which is product of consicutive and sum of all. without using sum() & diff() and using for loop

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

Answer 1

[James Tursa]

If the homework assignment specifies you must use a loop, then I don't think the intent was for you to wrap a simple i=1 range around vectorized code. That being said, I suppose your "loop" technically qualifies.

b is a vector. You simply need to sum all the elements of b and return that. s = s + b does not sum the element of b ... it simply creates a new vector s that is a copy of b. You need different code to sum the elements of b. There are various ways to do this, which I will let you figure out.

[Manav Divekar]

can you give some hints?

[Walter Roberson]

s+b(i)

[Manav Divekar]

its just gives sum of only first postion of the arrey.

[James Tursa]

How could you maybe change the for loop range so it added up all of the elements?

Answer 2

[Jan]

A hint: You want to perform this:

• s = 0
• s = s + 2*2
• s = s + 2*5
• s = s + 5*8

You need to loop over the indices of m. There is 1 iteration less than the number of elements of m.