# [R] Loop question?

David Hugh-Jones davidhughjones at gmail.com
Sat Jan 26 09:30:26 CET 2013

```Here's a toy example which you can apply the logic of:

dfr <- expand.grid(1:3,1:2)
results <- apply(dfr, 1, sum)
dfr[results==4,]

On 25 January 2013 22:19, Andras Farkas <motyocska at yahoo.com> wrote:
>
> Dear All
>
> I have the following data (somewhat simplyfied):
>
> TINF <-1
> a <-c(500,750,1000,1250,1500,1750,2000)
> b <-c(8,12,18,24,36,48,60,72,96)
>
> following function:
>
> infcprodessa <-function (D, tin, tau, ts)
>   (D * (1 - exp(-0.048 * tin))/(tin * (0.048*79) * (1 - exp(-0.048 * tau)))) * exp(-0.048 * (ts - tin))
>
> z <-sapply(1:1, function(n) infcprodessa(1000,TINF,12,12-TINF))
>
> is there a way to select the combination of respective a and b values that would result in a calculated z that is between 15 and 20? In this case the a would be 1000 and the b would be 12 (other combinations are also possible), but how could I automatically find them? perhaps a loop?
>
> Apreciate the help,
>
> Sincerely,
>
> Andras
>         [[alternative HTML version deleted]]
>
>
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