MATLAB: Question about initial value problem

initial value problem

I really do not understand what this question says to me. In those quarantina days, I am trying to learn matlab by myself by using Tobin's book. thus, I have no body to ask directly this question. Therefore, I posted this question without any my solution trial. sorry for that. any help, any suggestion any hint to give a way to solve this question will become very useful for me. Many thanks.

Best Answer

  • This question is similar to the one you posted earlier from this book, but this time, instead of giving a function handle as input, we are only giving vectors x and y. The interquad function does not know the input function and just need to rely on these data points to find the integral. To guess the value at a point, not in vector x, we use interpolation. Try the following code to
    x = 0:0.01:1;
    y = x.^2;
    a = interquad(x, y);
    function Q = interquad(x, y)
    f = @(xq) interp1(x, y, xq, 'pchip'); % phicp is recommended instead of cubic
    Q = quad(f, x(1), x(end));
    end
    It creates vectors x, and y from function on the interval . The output is as follow
    a =
    0.3333
    It is same as integral of on interval 0 to 1.