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## Re: Re: fsolve features

 From: Rolf Fabian Subject: Re: Re: fsolve features Date: Mon, 5 Jul 1999 15:12:09 +-200

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>> [x,RC]= fsolve(f='x^2 +1',randn(1)); #>V2.0.14
>>      #NOTE: prior to V2.0.14 , you have to  define  f  explicitely:
>>      #function y=f(x) y=x^2+1; end
>>      #[x,RC]=fsolve('f',randn(1))

> !!!  Where is this documented?

In octave V2.0.14 documentation  (

>>   (2)   a call to fsolve  like :  [x,info]=fsolve('f',x0)   is adequate for
>>  function   (vector) Y =  f ( vector X  )
>>        >>> where Y and X have same length <<<<
>>         It's supposed to handle equally sized problems only!

>>   It is easy to work around this.
>>   Maybe you are suggesting that a workaround
>>   is nt what you would like to have?

If this's SO EASY why didn't/don't YOU hack these obviously rather limited
couple
of  short program lines together and provide it to the public ?  Why didn'
anybody
else do such an EASY job within the last 5 years or so ...?

>>......
>>   Because of all these pitfalls of 'fsolve', I decided to write my my
>>   personal solver 'cfsolve' , returning correct complex roots for this (or
>>   similar) problem

cfsolve -algorithm development started in 1998 and  reached Version 4.1 up to
now !
Originally I planned to provide it to  octave community. But it's not published
yet, because
there are still some problems present associated with the operational mode of
'over-dimensioned' problems.
Equal-  and  under-dimensioned modes are very  well treated on the other hand.

Looking  back at more than one year's intense ( homebrew ... not full ) work
dealing with
this problem  while reading your statement above, I get in really great doubt,
whether my
conceptual approach  to the problem could be smart enough  to be efficient in
contrast
to your genious EASY solution !

Obviously, there seems to be no necessity anymore to finish this project from
my side ....

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