Re: fsolve shows repeated results

[Fausto Arinos de A. Barbuto]

On 16-10-2015 19:04, Nicholas Jankowski wrote:
> ok, I was curious:
>
>
>  >> xf = [0.1:0.5:5];
>  >> yf = xf.*tan(xf) - 42;
>  >> x = linspace(0,10,1000);
>  >> plot(x,x.*tan(x) - 42.0,xf,yf,'r*')
>
> seems to make sense now why one skipped over to the 7.6 value.  it's on a very 
> low slope section
> of the graph. something in the algorithm made it jump far to the right, and it 
> found itself on a
> new section to find a new zero.

Like the Newton-Raphson formula, whose 1st derivative f'(x) might intercept 
f(x) at
a point far away from the actual root, right? Makes total sense. Examining your 
plot
I observed though that there are other points on the same low-slope section of 
f(x).
And none 'misbehaved'. There's more in this case than meets the eye, I guess.

Fausto