The Epsilon class variable is used only when the primitives for some float functions are not available, in which case they are approximated to that precision. Using that same epsilon for something else is as meaningless as the 0.0001 in #closeTo:.

The epsilon really depends on your application.

- Bert -

On 27.02.2009, at 13:41, Oscar Nierstrasz wrote:

Yes, we looked at that, but closeTo: uses a much larger epsilon than Float's class variable Epsilon.

I suggested Camillo wrote an extension method similar to closeTo: but using the existing Epsilon (or an arbitrary one as an additional parameter).

Is that the right thing to do?

- on

On Feb 27, 2009, at 13:34, Lukas Renggli wrote:

Hi Camillo ;-)

Use the method #closeTo: instead of #=. Comparing floats with #=

almost never works.

Although "(Float halfPi / 2) tan" is printed as 1.0, it is not exactly

1.0 due to rounding errors in the calucaltaion and/or the internal

representation.

 (Float halfPi / 2) tan - 1.0 --> -1.110223024625156e-16

Lukas

--

Lukas Renggli

http://www.lukas-renggli.ch

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