If elements one array meet condition, use data in same element position in second array

Lets say I have an array of bearing angles such as: [0, 90, 0] and I want to use elements a that are equal to zero. I then want to use the data in another array of displacments [10, 10, 20], that are in the same positions as the angles that meet the condition in the first array. Im not sure how to do this, I figured out how to use the displacment and angle to then find x and y coordinates Im just not sure how to do this.

[That Guy]

note that these are just example arrays, im trying to write a code that i can use for different angle conditions, but I know how to do that portion im pretty sure.

Answer 1

[Ameer Hamza]

Read about logical indexing: https://www.mathworks.com/company/newsletters/articles/matrix-indexing-in-matlab.html

a = [0, 90, 0];
b = [10, 10, 20];

y = b(a==0)

Result

>> y
y =
    10    20