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Homework Help: Numerical stability

  1. Sep 19, 2005 #1
    Hi, here's my question...We have to determine whether or not the formulas down there are numerically stable for the cases where x >=0 and x<0. I say that the formulas are stable for x>=0 but not for x<0 because you are subracting numbers that could be close to each other. My problem is that I am having a really hard time writing a new formula that is numerically stable for negative x values. See if you can point me down the right path.
    the formulas are:

    u= +-sqrt((x+sqrt(x^2+y^2)))/2)


    Thanks for any help that you can give,
  2. jcsd
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