Calculate summation using loop?

I'm having trouble trying to put this summation: top of ∑ is N bottom of ∑ is j=1 side of ∑ is j^p For p=1,2,3 and N=6 how do i solve this using matlab? Could i have p=1,2,3 all under one script?

    clc
    j=1;
    p=1;
    sum=0;
    disp('j      p      j^p')
    disp('-----------------')
    while (j<=6)
        square=j.^p;
        sum=sum+square;
        fprintf('%d      %d      %d\n', j,p,square);
        j=j+1;

[per isakson]

Why not use a for-loop?

Answer 1

[Guillaume]

To make it easier for yourself, the first thing you should do is create a function for the summation. It takes two variables (N and p) and returns the result of the summation, like so:

function s = powersum(N, p)
  sum = 0;
  for j = 1:N
    %I'll leave you to fill this in, you've already done that in your script
  end
end

You can then use that function in your script for whichever value of N and p you wish:

N = 6;
for p = 1:3
  s = powersum(N, p);
  %do whatever you want with the result
end

Note that powersum can be implemented more efficiently without a loop but as it looks like you are a beginner in matlab, I'll leave it at that.

[Eugene]

Sorry Guillaume. We are told to use while or for loop only for this question.

[Guillaume]

The whole idea of a function is to make code easier to understand, but you can always replace a function call by the content of the function itself. In your case, just replace the

s = powersum(N, p);

in the for p=... loop with the content of the function, that is:

sum = 0;
for j = 1:N
  ...
end

[Eugene]

Yes Guillaume. I understand. Thanks for your help!!