Re: [Boost-users] math tools roots

Subject: Re: [Boost-users] math tools roots
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2011-10-09 12:48:43

AMDG

On 10/09/2011 06:47 AM, Matwey V. Kornilov wrote:
> 
> I believe that there is a bug in eps_tolerance implementation. At line 34 of 
> toms748_solve.hpp one can see:
> 
> return (fabs(a - b) / (std::min)(fabs(a), fabs(b))) <= eps;
> 
> When both a and b equal zero this condition is evaluated to a false instead 
> of a true. Left hand of condition is NaN and the right one is a floating-
> point number hence the result is false.
> 
> Well obviously, a user wants to see true here because the relative length of 
> interval in this case tend to zero.
> 

What exactly do you mean by "the relative length of
the interval tends to zero?"

lim_{(a,b)->(0,0)} |a-b| / min(|a|, |b|)

doesn't exist.

In Christ,
Steven Watanabe