Exam 2(c) Mon 7 Nov 2005

    1. Consider the points (0,0), (1,1), and (2,3).
      Use these points to compute the table of divided differences and give the Newton form of the interpolating polynomial through these points.
    2. Give an argument why the divided differences are independent of the order of the points, i.e.: f[x_0,x_1,x_2] = f[x_1,x_0,x_2].
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  1. Consider the quotient
                                             3  2
                                         1 - - x 
                                             4   
                                    q := --------
                                             1  2
                                         1 - - x 
                                             4   
    
    Compute a continued fraction representation of q. Count the number of arithmetical operations it takes to evaluate q, before and after the conversion.
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  2. Why does Romberg integration for the integral of f(x) over [a,b] use only even powers of 2? Explain.
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  3. Consider the values in the table below:
    +-----------------------------------------------------------------------------------------------+
    |  x  | 0.00000 | .125000 | .250000 | .375000 | .500000 | .625000 | .750000 | .875000 | 1.00000 |
    +-----------------------------------------------------------------------------------------------+
    |f(x) | 0.00000 | .382683 | .707107 | .923880 | 1.00000 | .923880 | .707107 | .382683 | 0.00000 |
    +-----------------------------------------------------------------------------------------------+
    
    Perform all your calculations with six significant decimal places.
    Write all numbers in scientific notation.
    1. To approximate f'(0.0), compute forward differences Delta f(0.0,h), for h=.5,.25,.125.
    2. Apply extrapolation using the values for Delta f(0.0,h).
    3. How accurate is your final approximation for f'(0.0)? Justify your answer.
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    1. Consider the quadrature rule
           b
          /
          |  f(x) dx = w0 f(a) + w1 f((a+b)/2) + w2 f(b). 
          /
           a
      
      Set up the system of equations in the weights w0, w1, and w2 to be satisfied for the highest possible algebraic degree of accuracy.
      Do NOT solve this system.
    2. What is the algebraic degree of accuracy attained by this rule?
      Justify your answer.
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