Where is the issue in my "while" statement?

Geo (view profile)

on 29 Jul 2017
Latest activity Answered by Teja Muppirala

Teja Muppirala (view profile)

on 30 Jul 2017
I want to evaluate the first integer evenly divisible by 3 and 5 using a Matlab code. My attempt is the following:
n=1;
while mod(n,5)~=0 && mod(n,3)~=0
n=n+1;
end
n
I'm new to Matlab and wondering where the issue here is. The code returns n=3 for some reason. I also want to extend this to find the first number evenly divisible by 1-10, for which I wrote the following while loop which also did not return the expected value. Where is my error?
n=1;
while mod(n,1:10)~=0
n=n+1;
end
n
Thank you.

Geo

Geo (view profile)

on 29 Jul 2017
I managed to fix the first one; I used "and" but it should've been "or" instead. I'm still stuck on the second.
Geo

Geo (view profile)

on 29 Jul 2017
Revision also not working as expected:
n=1;
for k=1:10
while mod(n,k)~=0
n=n+1;
end
end
n
Walter Roberson

Walter Roberson (view profile)

on 29 Jul 2017
found_solution = false;
n = 0;
while ~found_solution
n = n + 1;
found_solution = true;
for k = 1 : 10
if mod(n,k) ~= 0
found_solution = false;
break;
end
end
end
n

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Answer by the cyclist

the cyclist (view profile)

on 29 Jul 2017
Edited by the cyclist

the cyclist (view profile)

on 29 Jul 2017

In your second case, you are doing
mod(1,1)
then
mod(2,2)
then
mod(3,3)
and so on, because you are always incrementing n right along with k. Those mod functions are always equal to zero, so they always satisfy the while condition, so you get to n = 10.

Answer by Teja Muppirala

Teja Muppirala (view profile)

on 30 Jul 2017

You were on the right track. This gives 2520:
n=1;
while any( mod(n,1:10)~=0 )
n=n+1;
end
n
When your conditional has more than one element, all of them must be true for it to evaluate as true. This will return 'B' and 'C'.
if [1 1 1 0]
disp('A')
else
disp('B')
end
if [1 1 1 1]
disp('C')
else
disp('D')
end