I need to take a very large matrix that is generated by using the function `imread()`. This turns an image (mine is a jpg file; 691x763) into a matrix.

I need to divide each element in the matrix by 255 and show each element with at least 3 decimal places.

**What I've tried:** 

`output_precision(4)` but it didn't work for the elements inside the matrix.

`format long e` but the values inside the matrix were still unaffected.