MATLAB: How to enter this program

basichomeworkprogramming

Hello, I have tried unsuccessfully for a couple hours to enter a program that loops until a number that is even, divisible by both 13 and 16, and whose square root is greater than 120 is found. I have reached a wall, so I have come to ask for help. Would using a while statement be the first step? Please don't solve this problem, I only ask for help getting it going. Yes, this is basic stuff, but I still have little understanding on it.

Best Answer

You need to translate each of those conditions into a matlab logical proposition. For example if n is an integer you are investigating, try dividing it by 13, then comparing the 'round' of the quotient with the original quotient to see if it is still an integer after the division. And yes, the 'while' function is the right thing to use here. Keep it looping until all the conditions turn out to be true for the same integer, for which you can make great use of the "&" operation.

Related Solutions

MATLAB: Logical operators with while loop

At the risk of doing someones homework :P

clc;
clear;
x = 0; % or start at x = 86^2;
while true
    a = rem(x,13);
    b = sqrt(x);
    if a==0 && b>86
        fprintf('The required number is %d\n',x);
        break;
    else
        x=x+2;
    end
end

MATLAB: Run a program to display the least possible integer divisible by 11 and its square root greater than 132

While Jose is correct, the answer is trivial, even with a loop. What is the requirement? The requirement is that

SQRT(x) > 132

You wrote

x^2 > 132

There is a BIG difference. :) Simply making that change in your code will fix the problem.

Hint: You can solve it far more easily though. Rather than checking if rem(x,11)==0, why not change things around? If you ONLY look at multiples of 11, you know that ALL multiples of 11 are divisible by 11. (Sort of a truism.) The advantage is then you never need to check if rem(x,11)==0. You know that to be true in advance.

Since you really did solve the problem already except for that minor inversion...

x = 11;
while sqrt(x) <= 132
  x = x + 11;
end

As you can see, x covers all multiples of 11, stopping as soon as sqrt(x) exceeds 132.

Can you do better yet? Of course, if you think carefully about the requirements. If you know that sqrt(x) > 132, then since we know that 132 is divisible by 11, then 132^2 is also divisible by 11. But you want the smallest integer that is divisible by 11 and the sqrt is STRICTLY GREATER than 132. So just add 11.

x = 132^2 + 11
x =
       17435

I'm not sure that this final result is what your instructor wants to see though.

Best Answer

Related Solutions

MATLAB: Logical operators with while loop

MATLAB: Run a program to display the least possible integer divisible by 11 and its square root greater than 132

Related Question