WHILE LOOP program does not work

Please, any one tell me why my program does not work, thank you.

This is my program

a=[7 18 11 5;
   2 8 10 13;
   3 24 20 12;
   21 1 20 17];

[m,n]= size(a);

Re=0;
i=1;

while i<=m;
   j=1
while j<=n;

if ((a(i,j)<=15) & (a(i,j)>=4))
    Re= Re+ a(i,j);
end

end

end
disp(Re)

[Walter Roberson]

In order for people to tell you why your program does not work, you have to tell them what the intended working of the program is.

Answer 1

[Image Analyst]

Try it without loops, in a more MATLAB-ish vectorized way:

indexesToSum = a>=4 & a<=15
Re = sum(a(indexesToSum))

[sss dzu]

thank you

Answer 2

[Matt Fig]

You do not increment i or j inside the loops.

i =i+1;

etc. Thus i will always be less than m, and j less than n.

[sss dzu]

I tried before, but it did not work either

Answer 3

[sss dzu]

but i have to use while loop