"Rau, Roland" <[EMAIL PROTECTED]> writes:
> Dear R-Helpers,
>
> I have a matrix where the first column is known. The second column is
> the result of multiplying this first column with a constant "const". The
> third column is the result of multiplying the second column with
> "const".....
> So far, I did it like this (as a simplified example):
>
> nr.of.columns <- 4
>
> myconstant <- 27.5
>
> mymatrix <- matrix(numeric(0), nrow=5, ncol=nr.of.columns)
>
> mymatrix[,1] <- 1:5
>
> for (i in 2:nr.of.columns) {
> mymatrix[,i] <- myconstant * mymatrix[,i-1]
> }
>
>
> Can anyone give me some advice whether it is possible to avoid this loop
> (and if yes: how)?
>
How about:
> myconstant <- 27.5
> a <- 1:5
> myconstant <- myconstant^((1:nr.of.columns)-1)
> myconstant
[1] 1.00 27.50 756.25 20796.88
> mymatrix <- outer(a,myconstant)
> mymatrix
[,1] [,2] [,3] [,4]
[1,] 1 27.5 756.25 20796.88
[2,] 2 55.0 1512.50 41593.75
[3,] 3 82.5 2268.75 62390.62
[4,] 4 110.0 3025.00 83187.50
[5,] 5 137.5 3781.25 103984.38
>
HTH
Zoltan
> Any suggestions are welcome!
>
> Thanks,
> Roland
>
>
>
>
> +++++
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>
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--
Z. Barta
Dept. of Evol. Zool., Univ. of Debrecen, Debrecen, H-4010, Hungary
Phone: 36 52 316 666 ext. 2334, Fax: 36 52 533 677
E-mail: [EMAIL PROTECTED], http://puma.unideb.hu/~zbarta/
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