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Re: Problems with fzero
From: 
John W. Eaton 
Subject: 
Re: Problems with fzero 
Date: 
Thu, 31 Oct 2002 18:44:51 0600 
On 31Oct2002, Schloegl Alois <address@hidden> wrote:
 x=10:.001:10;
 y=x1.092.7217*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 nonzero imaginary
part,
 a warning (or error) message should appear.
Yes, if you are using fsolve and one of the sampled values of your
function is complex, Octave should print
warning: implicit conversion from complex scalar to real matrix
In the next development snapshot, Octave will also print
warning: fsolve: ignoring imaginary part returned from usersupplied function
the first time this happens on any given call to fsolve.
jwe

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