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Homework Help: Quantitative Methods: Numerical Solution of DEs

  1. Mar 19, 2009 #1
    1. The problem statement, all variables and given/known data

    Show that if we fit f(x) over [xn,xn+1], with a first-degree polynomial that interpolates f at xn and xn+1, then f(x)=f(xn)+[f(xn+1)-f(xn)](x-xn)/h. Putting that approximation into the relevant equation 1 which is given at relevant equations part derive the approximation:

    2. Relevant equations

    eq.1 : y(xn+1) = y(xn) + f(xn+1) - f(xn)

    Also we know that y'=f(x) and y(xn+1)=y(xn)+f(xn)h
  2. jcsd
  3. Mar 19, 2009 #2


    Staff: Mentor

    What have you done? If you haven't done so, draw a picture. Your interpolation polynomial is first-degree, which means it's a straight line.
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