feval==>it will evaluate a function and gives output depending upon the input. input may be in n numbers and output may also be in n numbers.
write a function then use this your function or function from library in inverted comma or with the @ symbol and follow the syntax.
to know the size of a matrix you dont have to use ‘r ‘and ‘c’ to store the row and column instead enter some any other variable.
‘find’ function will give the linear index of the matrix so use accordingly.