Float.finite ?

[Aldric Giacomoni]

How does one use .finite? effectively? I tried with (1.0/3).finite? => true...
I tried with BigDecimal.. Still true. I'm pretty sure these numbers aren't
finite. How do I make this work?

--
Aldric Giacomoni<br>
Time does not count itself. You have only to look at a circle and this is
apparent.

-- Leto II (The Tyrant)

 

[Todd Benson]

How does one use .finite? effectively? I tried with (1.0/3).finite? => true...
I tried with BigDecimal.. Still true. I'm pretty sure these numbers aren't
finite. How do I make this work?

1.0/3 is most certainly finite. Here is how #finite? works...

irb(main):001:0> 1.0/0
=> Infiinity
irb(main):002:0> (1.0/0).finite?
=> false
irb(main):003:0> (-1)**0.5
=> NaN
irb(main):004:0> ((-1)**0.5).finite?
=> false

Todd

 

[Stefano Crocco]

Alle Friday 10 April 2009, Aldric Giacomoni ha scritto:

How does one use .finite? effectively? I tried with (1.0/3).finite? =>
true... I tried with BigDecimal.. Still true. I'm pretty sure these numbers
aren't finite. How do I make this work?

According to the ri documentation, Float#finite? only returns false if self is
not inifinite and self.nan? is false. For example,

(1/0.0).finite?
=> false

What you wanted to know is whether the number has a finite or infinite number
of decimal digits. Unfortunately, I don't think such a method exists. You
can't do that with floats, because all floats have a finite number of decimal
digits (you can't very well store infinite digits in your computer's memory,
after all). I suppose it can be done with the Rational class, but you'd have
to write the method yourself. Here's a simple example of how this could be
done:

require 'rational'

class Rational

def finite_digits?
d = denominator
return false if d % 2 !=0 and d % 5 != 0
d = d / 2 while d % 2 ==0
d = d / 5 while d % 5 == 0
d == 1
end

end

Stefano

 

[Aldric Giacomoni]

Ah! Understood. Thank you.. Big help

Alle Friday 10 April 2009, Aldric Giacomoni ha scritto:

According to the ri documentation, Float#finite? only returns false if self is
not inifinite and self.nan? is false. For example,

(1/0.0).finite?
=> false

What you wanted to know is whether the number has a finite or infinite number
of decimal digits. Unfortunately, I don't think such a method exists. You
can't do that with floats, because all floats have a finite number of decimal
digits (you can't very well store infinite digits in your computer's memory,
after all). I suppose it can be done with the Rational class, but you'd have
to write the method yourself. Here's a simple example of how this could be
done:

require 'rational'

class Rational

def finite_digits?
d = denominator
return false if d % 2 !=0 and d % 5 != 0
d = d / 2 while d % 2 ==0
d = d / 5 while d % 5 == 0
d == 1
end

end

Stefano

 

[Aldric Giacomoni]

I see. Thank you..I misunderstood what the function did