MATLAB: Summation after looping

loopsumsummation

I got a problem with summation after looping. Here is the problem :
——————————————
for ri = 0:3
        if ri == 0
           mi = 1
        elseif i > 0
           mi = 1
        end  
end
r = sum(ri)
——————————————
I'm expecting the result from r was 6 (0+1+2+3) but its result was 3. I think the sum command only read the last ri which is 3 and neglecting the other ri.
Any answer will be appreciated. Thanks!

Best Answer

When you use the 'for' statement, you iteratively set ri to each of the values 0, 1, 2, 3. Thus ri only contains 3 after the loop. Instead, assign ri=0:3 to a different variable and have the for loop iterate over that.
For example,
    rr = 0:3;
    for ri=rr,
       if ri == 0
             mi = 1
          elseif i > 0
             mi = 1
          end  
    end
    r = sum(rr);  %this will be 6
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