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Homework Help: Relative error between a real and complex number.

  1. Nov 23, 2008 #1
    1. The problem statement, all variables and given/known data
    So I've got a polynomial with real roots. It turns out that if you perturb one of the coefficients by a small amount, two of the roots end up in the complex plane. Now I want to find the relative error in my computation. For two real numbers, say x1 and x2, I would take
    [tex]rel.err. = {{x1-x2}\over{x1}}[/tex].
    But what do I do if x1 is real and x2 is complex?


    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Nov 23, 2008 #2

    olgranpappy

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    Homework Helper

    mabye try
    [tex]
    \frac{|x_1-x_2|}{x_1}
    [/tex]
     
  4. Nov 23, 2008 #3
    Yes. That makes sense. It is the distance between the two values. Works in the complex plane too. Thanks.
     
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