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## Re: Problems with fzero

**From**: |
Schloegl Alois |

**Subject**: |
Re: Problems with fzero |

**Date**: |
Thu, 31 Oct 2002 19:24:18 +0100 (MET) |

**User-agent**: |
IMP/PHP IMAP webmail program 2.2.8 |

see
x=-10:.001:10;
y=x-1.09-2.7217*log(1+(x/2.7217));
plot(x,real(y'*[1,-i]))
Based on this graph, the solutions 3.2106 and -1.7701 are correct.
for all x<2.7217, y(x) is complex. It looks like FZERO (and FSOLVE) look only
for the real part of the function y(x). If y(x) has a non-zero imaginary part,
a warning (or error) message should appear.
Alois
Zitiere Diego Ruiz Moreno <address@hidden>:
>* Hello all,*
>* I have a BIG problem with fzero*
>* I have a "strange" function that is y =*
>* x-1.09-2.7217*log(1+(x/2.7217));*
>* When I ask to fzero with a positive initial numbre, let X0= 5, the *
>* answer is correct, it is 3.2106, but if I give an negative initial point*
>* *
>* (-1) the answer is -1.7701 That is not correct, and more if I call it *
>* with -5 tyhe answer is -3.2701, and finally if I call it with -51the *
>* aswer is correct.*
>* Could somebody explain to me this behavior ??*
>* *
>* Thanks.*
>* *
>* Diego*
>* *
>* *
>* *
>* *
>* *
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Octave is freely available under the terms of the GNU GPL.
Octave's home on the web: http://www.octave.org
How to fund new projects: http://www.octave.org/funding.html
Subscription information: http://www.octave.org/archive.html
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