java natural exponential and 'Infinity'

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NoIdea - 22 Mar 2006 16:49 GMT

how do you test for an infinite result given by the Java Math.exp()
function?

i need to do something like :-

if (Math.exp(200) "is infinite" ) {
{do something}
}

i've tried enclosing "Infinity" in quotes but it seems to think I'm
treating it as a string. Anyone any ideas how to do this?

Thanks

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Thomas Weidenfeller - 22 Mar 2006 17:07 GMT

> how do you test for an infinite result given by the Java Math.exp()
> function?
[quoted text clipped - 7 lines]
> i've tried enclosing "Infinity" in quotes but it seems to think I'm
> treating it as a string. Anyone any ideas how to do this?

Double.POSITIVE_INFINITY
Double.NEGATIVE_INFINITY

/Thomas

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Oliver Wong - 22 Mar 2006 17:21 GMT

Thomas gave you the answer. I just wanted to clarify that whenever you
enclose something in double-quotes, Java will always treat that as a String.
If you enclose something in single-quotes, it will always be treated as a
char.

- Oliver

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Patricia Shanahan - 22 Mar 2006 17:28 GMT

> how do you test for an infinite result given by the Java Math.exp()
> function?
[quoted text clipped - 9 lines]
>
> Thanks

if( Double.isInfinite(Math.exp(200)) )

Double has a lot of utility methods, so it is a good idea to check its
javadoc if you are stuck trying to do something about a double.

Patricia

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Roedy Green - 22 Mar 2006 20:21 GMT

>if (Math.exp(200) "is infinite" ) {
> {do something}
>}

see http://mindprod.com/jgloss/floatingpoint.html#NAN
and
http://mindprod.com/jgloss/gotchas.html#NAN

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Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

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Chris Smith - 22 Mar 2006 21:24 GMT

> >if (Math.exp(200) "is infinite" ) {
> > {do something}
[quoted text clipped - 3 lines]
> and
> http://mindprod.com/jgloss/gotchas.html#NAN

Since this came up recently, you may want to clarify on that page that
dividing by zero does not result in NaN, unless the numerator is also
zero. Generally, it results in an infinity of the appropriate sign.

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Roedy Green - 22 Mar 2006 22:21 GMT

>Since this came up recently, you may want to clarify on that page that
>dividing by zero does not result in NaN, unless the numerator is also
>zero. Generally, it results in an infinity of the appropriate sign.

done

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Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

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java natural exponential and 'Infinity'

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