Hi,
I was taking a look to the code of the function zbrent (Brent's method, Fortran 77 2nd ed.) and I saw this line of code:

if(abs(xm).le.tol1.or.fb.eq.0.) then

Shouldn't this type of expression be replaced to avoid strange results? Because of the comparison fb.eq.0.

Ricardo

Hi Ricardo,

The method converges because of the first test. The test for fb.eq.0 is there only to take care of the special case when fb really is exactly zero.

Saul Teukolsky