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Homework Help: Interpolation in matlab

  1. Oct 25, 2009 #1
    1. The problem statement, all variables and given/known data

    If i have an interpolation formula, say:

    [tex]y(t_i)=3+h\sum^i_{j=1}jy(t_j)[/tex]

    where i=0 to n
    h=(a+b)/n
    ti=i*h
    and
    when i=0, we have: y(t0)=0.

    How would i write a code to find y(ti)?

    2. Relevant equations



    3. The attempt at a solution

    function y=examp(a,b,n)
    h=(a+b)/n
    for i=1:n+1
    t(i)=(i-1)*h
    for j=1:i+1

    and now im stuck because i dont know how write a code that uses the previous value of y to compute the next value of y.
     
  2. jcsd
  3. Nov 3, 2009 #2
    Before the first loop, I would set up the y's(actually, it would be faster for your code to init the t's to zeros to, but unless n is very large it shouldn't matter):

    y = zeros(n+1,1)

    Then in the loop it would be something like
    y(j) = 3 + sum( y(1:j-1).*(1:j-1) )

    the .* does an element-wise product
     
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