ERROR: Throw not defined

[BigCrunsh]

Hey

I was running the following code:

using Distributions
f=x->cdf(Beta(2,2),x)-0.015
fzero(f, eps())

Unfortunately, this throws a blank error message. Has somebody an idea?

Thanks, Christoph

[stevengj]

I get an fzero not defined error. fzero is not a built-in function in Julia. Are you using some other package too?

[simonster]

@stevengj fzero is a function in Roots, so you also need using Roots. I get:

ERROR: Throw not defined
 in SOLVE at /home/simon/.julia/Roots/src/SOLVE.jl:45
 in derivative_free at /home/simon/.julia/Roots/src/derivative_free.jl:308
 in fzero at /home/simon/.julia/Roots/src/Roots.jl:114

It looks like this line should call throw and not Throw (edit: fixed in 141e2f1). Then you get a PossibleExtremaReached error. The beta distribution only has support on [0, 1], so you probably want to call fzero(f, 0, 1).

[simonster]

However, this seems like a bug:

julia> fzero(f, eps(), [0.0, 1.0])
-0.014999999999999777

[jverzani]

That's definitely a bug. The extra starting point isn't even that helpful, so perhaps its best to deprecate starting points when there is a bracket specified.

julia> fzero(f,  [0.0, 1.0])
0.07248365539489167

[BigCrunsh]

thx @simonster

[jverzani]

Calling with a bracket and initial point should work now:

julia> fzero(f, eps(), [0.0, 1.0])
0.07248365539489167

Thanks