Re: Using fsolve() for a function involving quad()?

[Minyu Chen]

Thank you very much.

For my case, this reply by JWE in someone else's post works: http:// 
www.nabble.com/How-to-share-variables-between-functions-p9812339.html

Here are my entire test:

function w=f(x,y)
w=x.*y;
end

function z=g(x)
z=quad(@(y)f(x,y),0,1)+2;
end

And "fsolve('g',0)" return the correct answer 4.

Thanks,
Minyu Chen

On Jun 12, 2007, at 7:05 PM, David Grohmann wrote:

> Minyu Chen wrote:
> > Dear all:
> >
> > I am sorry that the question might sound a bit silly.
> >
> > I need to solve a function involving integration, so I think I  
> > need  both quad()--for the integration and fsolve()--for the  
> > equation.  However, the integrand involve the unknown.
> >
> > For a trivial example, I want to solve: x+\int_{0}^{1}x*y dy=0
> >
> > I was thinking of taking a function:
> >
> > function w=f(y)
> > w=x.*y;
> on this line what 'x' do you expect to have? you need to pass your  
> x in from g() to f() if that is the x you though tit would be.
> > endfunction
> >
> > Then I use another function:
> >
> > function z=g(x)
> > z=quad('f',0,1)+x;
> > endfunction
> >
> > Then I use: fsolve('g',0.5). But it didn't work.
> >
> > The error message is that the "x" is not defined in my f  
> > function.  However, I called "f" only in the function "g", and the  
> > x in the  function "g" is already initialized as 0.5 in the  
> > searching. What  went wrong?
> >
> > Thank you very much.
> >
> > Thanks,
> > Minyu Chen
> > _______________________________________________
> > Help-octave mailing list
> > address@hidden
> > https://www.cae.wisc.edu/mailman/listinfo/help-octave
>
>
> --
> David Grohmann
> Senior Student Associate
> Applied Research Lab : UT Austin : ESL - S206
> Office: 512-835-3237