Creating a new matrix from an existing one using logical operators?

Write a script which defines a 100x100 matrix, X, of random integers between 5

and 50. From the matrix X, create a matrix, Y, in which all values greater than or

equal to 25 are the same as in X, but all values below 25 are changed to 0.

Here is what I have:

x=randi([5 50],100,100)
Y=randi([5 50],100,100)
if Y>25
    disp(Y)
elseif Y<25
    disp(0)
end

The matrix that I am getting in the out put is not correct. No numbers have been substituted with zero.

[the cyclist]

If you look at the documentation on the if function, you'll see that in the "Compare Arrays" section, it says

"Expressions that include relational operators on arrays, such as A > 0, are true only when every element in the result is nonzero."

So, your if statement is not testing each element and then giving a result for each element, as you seem to expect. It is testing the entire array, to see if it is true for all elements.

[Trisha Katz]

Okay, I understand, but how can I get it search for specific values within the matrix? i have tried googling and looking through my text to no avail

Answer 1

[David Hill]

x=randi([5 50],100,100);
y=(x>=25).*x;