Re: Help-octave Digest, Vol 45, Issue 10

[Jaroslav Hajek]

On Mon, Dec 7, 2009 at 8:19 PM, Bart Vandewoestyne
<address@hidden> wrote:
> On Mon, Dec 07, 2009 at 09:02:51AM -0600, address@hidden wrote:
>>
>> The style of supplying Jacobian is not supported in the 3.2 version of
>> fsolve. Instead, one should use the Matlab-compatible style:
>>
>>  function [y,J] = f_3d(x)
>>
>>  y(1) = 16*x(1)^4 + 16*x(2)^4 + x(3)^4 - 16;
>>  y(2) =    x(1)^2 +    x(2)^2 + x(3)^2 - 3;
>>  y(3) =    x(1)^3 -    x(2);
>>
>> if (nargout > 1)
>>  J = zeros(3,3);
>>  J = [64*x(1)^3 64*x(2)^3 4*x(3)^3; ...
>>        2*x(1)    2*x(2)   2*x(3);   ...
>>        3*x(1)^2   -1      0];
>> endif
>>
>>
>> I think this style is preferable not only because of
>> Matlab-compatibility, but also because y and J are usually closely
>> related. It wouldn't be hard to support also the old version, but the
>> fact is that it is not there, because nobody asked for it.
>
> OK.  Thanks.  In the meanwhile, i also found that this was the
> solution to my problem.
>
>> Apparently the manual wasn't updated. But it has the docstring
>> included; so you should pay attention to that.
>
> I'm afraid I don't understande what you mean here.  Can you
> explain a bit?
>
> Kind regards,
> Bart
>

The fsolve function was completely rewritten as an m-file between 3.0
and 3.2. Matlab compatibility was a major point; also the rewrite
removed some limitations of the old MINPACK wrapper and adds a number
of improvements.
The function's docstring (as displayed by "help fsolve") is
up-to-date, because I rewrote it along the code change;
but apparently I missed the extra examples in the manual.
This is general: when a function is rewritten or significantly
modified, the docstring is easily updated because it's in the same
file. Scanning through the manual for other leftovers is something I
typically put off till later; then forget about it :)

Now the question is: should we add back the support for address@hidden, @jac} 
style?

-- 
RNDr. Jaroslav Hajek
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz