How to compare the index values in the different matrices

Hello,

I am trying to solve the problem 23 in Introduction to Matlab. The question asks to find the perfect squares as shown below. You can see that both 2 and 2^2 are in the same matrix.

Input a = [2 3 4]
Output b is true

I want to compare the input matrix with the root squared one but I do not know how to compare . Here is my code but it does not work. Is there any function for doing that?

a = [2 3 4]
b = sqrt(a)
if a == b
    disp('b is true')
else
    disp('b is false')
end

Answer 1

[Adam Danz]

See isequal.

or ismember

Demo:

a = [2 3 4]

a = 1×3

2 3 4

b = sqrt(a)

b = 1×3

1.4142 1.7321 2.0000

ismember(a,b)

ans = 1×3 logical array
   1   0   0

To understand why your conditional statement does not work, consider this example below.

if [true false false]
    disp('TRUE')
else
    disp('FALSE')
end

FALSE

if [true true true]
    disp('TRUE')
else
    disp('FALSE')
end

TRUE

[Utku Ceylan]

Thanks for the answer. I understood why my if condition is wrong. However, I could not get how I can use isequal for this.

[Adam Danz]

I'm not familiar with the Intro to Matlab problems but from your question question, "I want to compare the input matrix with the root squared one but I do not know how to compare", by compare do you mean you want to test whether A equal B or do you want to do an element-wise comparison?

[Utku Ceylan]

I want to find if the root squared value in "b" exists "a".

[Adam Danz]

I see. I've updated my answer.

Use ismember or ismembertol.

[Utku Ceylan]

Thanks a lot. I changed my code which can be seen below. However, I could not pass almost all the tests although I got the desired result. I still do not get what is wrong with my code.

a = [2 3 4]
b = sqrt(a)
 
if any(ismember(b,a)) == 1
     disp('b is true')
 else
     disp('b is false')
end

Let me copy and paste the question without changing. The question is in the "Introduction to MATLAB" problem group. The question says that:

[Adam Danz]

I don't know what tests are performed but the code you shared produces the correct results. However, there is no need for the "==1" in your any() comment.