R help - Jul 2006 - 0* log(0) should be zero but NaN

Dear R-users
>prob <- c(0.5,0.4,0.3,0.1,0.0)
>cal <- prob * log(prob,base=2)
>cal
[1] -0.5000000 -0.5287712 -0.5210897 -0.3321928        NaN

Is there any way to change NaN to zero ?

I did come up with this by applying Ripley's relpy to my previous question

cal <-prob*log(pmax(prob,0.00000001),base=2)

Any suggestion ?

Thank you

Taka

> prob <- c(0.5,0.4,0.3,0.1,0.0)
> cal <- prob * log(prob,base=2)
> cal
[1] -0.5000000 -0.5287712 -0.5210897 -0.3321928       
NaN
> cal[is.nan(cal)] <- 0
> cal
[1] -0.5000000 -0.5287712 -0.5210897 -0.3321928 
0.0000000
>

On 7/11/06, Taka Matzmoto <sell_mirage_ne@hotmail.com>
wrote:
>
> Dear R-users
>
> >prob <- c(0.5,0.4,0.3,0.1,0.0)
> >cal <- prob * log(prob,base=2)
> >cal
> [1] -0.5000000 -0.5287712 -0.5210897 -0.3321928        NaN
>
> Is there any way to change NaN to zero ?
>
> I did come up with this by applying Ripley's relpy to my previous
question
>
> cal <-prob*log(pmax(prob,0.00000001),base=2)
>
> Any suggestion ?
>
> Thank you
>
> Taka
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
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>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390 (Cell)
+1 513 247 0281 (Home)

What is the problem you are trying to solve?

	[[alternative HTML version deleted]]

Try this:

p <- 0:10/10
p * log2(p + !p)

On 7/11/06, Taka Matzmoto <sell_mirage_ne at hotmail.com>
wrote:
> Dear R-users
>
> >prob <- c(0.5,0.4,0.3,0.1,0.0)
> >cal <- prob * log(prob,base=2)
> >cal
> [1] -0.5000000 -0.5287712 -0.5210897 -0.3321928        NaN
>
> Is there any way to change NaN to zero ?
>
> I did come up with this by applying Ripley's relpy to my previous
question
>
> cal <-prob*log(pmax(prob,0.00000001),base=2)
>
> Any suggestion ?
>
> Thank you
>
> Taka
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>