Implement an equation with a substraction and division of two arrays

I want to implement this equation in Matlab

The a values are in an array of 140x1 double called approx, the values of x are also in an array of 140x1 double called subArray, and n is an array 1x1 with a value equal to 140.

I am using the following code:

MRE=(1/n)*(abs(approx(:,1)- subArray(:,1))/abs(subArray(:,1)));

but Im getting the following error

Unable to perform assignment because the left and right sides have a different number of elements.

How could I implement this equation in Matlab?

Answer 1

[Sara Alonso Vicario]

Here you want element-wise division. Also don't forget the summation:

MRE = (1/n) * sum((abs(approx - subArray) ./ abs(subArray)));

^^^ ^

Using some random data:

clc, clear, rng(3);

n = 140;

approx = rand(n, 1);

subArray = rand(n, 1);

MRE = (1/n) * sum((abs(approx - subArray) ./ abs(subArray)))

% MRE =

%

% 4.2877

(answer by the user tdy in stackoverflow)