MathGroup Archive 2008

[Date Index] [Thread Index] [Author Index]

Search the Archive

Two FindRoot questions


These are not FindRoot questions, per se...

Here's a simple example which I want to ask three questions about:

f[k_] := x /. FindRoot[x^2 + k, {x, 0, 10}];
Plot[f[k], {k, -10, 10}]

First, I want the plot to only show where there exists a root.
Is the right solution to make f[] return Null?
How do I make f[] return Null? (Is there a way to "catch" the

Finally, I need to solve my equations to 20 digits. How do I do that?
I've read about Accuracy and Precision but it didn't help.


  • Prev by Date: Built-in Cross is slow
  • Next by Date: strange behaviour of background color in Panel[]
  • Previous by thread: Built-in Cross is slow
  • Next by thread: Re: Two FindRoot questions