# [R] Looking for simpler solution to probabilistic question

Rainer M Krug R.M.Krug at gmail.com
Tue Jan 15 13:53:06 CET 2008

```Hi Dimitris

that was EXACTLY what I was looking for

Thanks

Rainer

Dimitris Rizopoulos wrote:
> matrix(age1, ncol=length(age1), nrow=length(age2), byrow=TRUE) + age2
>
> can be replaced by
>
> outer(age2, age1, "+")
>
> and the same for 'p'.
>
>
> Best,
> Dimitris
>
> ----
> Dimitris Rizopoulos
> Ph.D. Student
> Biostatistical Centre
> School of Public Health
> Catholic University of Leuven
>
> Address: Kapucijnenvoer 35, Leuven, Belgium
> Tel: +32/(0)16/336899
> Fax: +32/(0)16/337015
> Web: http://med.kuleuven.be/biostat/
>     http://www.student.kuleuven.be/~m0390867/dimitris.htm
>
>
> ----- Original Message ----- From: "Rainer M Krug" <R.M.Krug at gmail.com>
> To: "r-help" <r-help at stat.math.ethz.ch>
> Sent: Tuesday, January 15, 2008 1:24 PM
> Subject: [R] Looking for simpler solution to probabilistic question
>
>
>> Hi
>>
>> I have two processes which take with a certain probability (p1 and p2) x
>> number of years to complete (age1 and age2). As soon as thge first
>> process is completed, the second one begins. I want to calculate the
>> time it takes for the both processes to be completed.
>>
>> I have the following script which gives me the answer, butI think there
>> must be a more elegant way of doing the calculations between the #####
>>
>> Any ideas welcom,
>>
>> Rainer
>>
>>
>> age1 <- 1:20
>> p1 <- dnorm(age1,10,2)
>>
>> age2 <- 10:30
>> p2 <- dnorm(age2,15,1)
>>
>> ######
>> age <- matrix(age1, ncol=length(age1), nrow=length(age2), byrow=TRUE)
>> + age2
>>
>> p <- matrix(p1, ncol=length(p1), nrow=length(p2), byrow=TRUE) + p2
>> p <- as.numeric(tapply(p, age, sum))
>> p <- p / sum(p)
>> #####
>>
>> age <- sort(unique(as.numeric(age)))
>>
>> plot(age, p)
>>
>> lines(age1, p1)
>> lines(age2, p2)
>>
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