# Re: (expt 2 #c(2d0 0))?

*From*: Raymond Toy <toy.raymond@xxxxxxxxx>*Date*: Sun, 16 May 2010 11:31:31 -0400

"Barry" == Barry Margolin <barmar@xxxxxxxxxxxx> writes:

Barry> In article

>> > What makes you think the origial 2.0 and 3.0 are exact? They

>> > came from

>>

>> On the other hand, what makes you think they weren't exact?

>> Any epsilon you want to ascribe is outside of the computation.

Barry> When using transcendental functions, exact numbers are

Barry> extremely rare. Except for special cases, all their

Barry> results are irrational, so the floating point value will be

Barry> an approximation.

Certainly, but saying the result of a transcendental function is a

floating-point approximation doesn't give you freedom to return any

value. There's a certain expectation that some care is taken and the

value is as close to the true value as reasonably possible.

Perhaps I'm being unreasonable. :-)

I agree that the spec doesn't explicitly say what the accuracy of

(expt 2 #c(-2d0 -1d0)) should be. It would be nice if the more

accurate value were returned, since that doesn't violate the spec,

AFAICT.

Ray

.

**Follow-Ups**:**Re: (expt 2 #c(2d0 0))?***From:*vanekl

**References**:**(expt 2 #c(2d0 0))?***From:*Raymond Toy

**Re: (expt 2 #c(2d0 0))?***From:*Barry Margolin

**Re: (expt 2 #c(2d0 0))?***From:*Raymond Toy

**Re: (expt 2 #c(2d0 0))?***From:*Captain Obvious

**Re: (expt 2 #c(2d0 0))?***From:*Raymond Toy

**Re: (expt 2 #c(2d0 0))?***From:*Captain Obvious

**Re: (expt 2 #c(2d0 0))?***From:*Raymond Toy

**Re: (expt 2 #c(2d0 0))?***From:*Barry Margolin

**Re: (expt 2 #c(2d0 0))?***From:*Raymond Toy

**Re: (expt 2 #c(2d0 0))?***From:*Barry Margolin

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