1) Write a generic function to integrate y(x)dx with the following format function I integrator (x, y, method) where x is a vector and y is a matrix whose columns y(:,j) are vectors of the same length as x and contain equally spaced data points. The output I is a row vector whose elements are the integrals of each column of y with respect to x. In other words, the jth element of I is I(j) = * y(:,j)dx. method is the technique used, and should either be the string 'trap' for the trapezoidal rule or 'simp' for Simpson's 1/3 rule. If the method argument is missing in the integrator function call, the default method should be set to the trapezoidal rule (Hint: look up how to vary the number of input arguments in a function call). The integrator function should evaluate the number of intervals to integrate and should check that this number is even when Simpson's 1/3 is selected; if that's not the case, the function should stop and print an error message warning the user. The integrator function should contain 2 subfunctions (local functions), one to implement the trapezoidal rule and one to implement Simpson's 1/3 rule. No loop should be used (use vector operations only). Check your subfunctions with simple problems for which you know the answer.