Write three functions, AppEval, AppDeriv and AppInt that approximate the value, the derivative and the integral of an unknown function f for which you are given only some unevenly spaced values. More specifically, the function AppEval has to be written

Question

in the file AppEval.m, and its first line looks like this:

function y=AppEval(x,xvals,yvals)

For any x from the interval [0, 1] it should return (an approximation of) the function value y = f (x). You do not know the formula for f , but xvals and yvals are sample vectors of length approximately 120 (you cannot rely on the exact length but it will be
larger than 100). For each element of xvals, the function value is in yvals: yvals(i) is f(xvals(i)). Note that the values in xvals cover the entire range from -0.1 to 1.1but they are slightly unevenly spaced in a random manner.