[R] Creating a matrix with an unknown variable

[David Carlson]

Another approach passing both D and delta:

> Afct <- function(D, delta) exp(-(outer(D, D, "-")/delta)^2)
> D <- c(-1, -2/3, -1/3, 0, 1/3, 2/3, 1)
> Delta <- 2
> Afct(D, delta)

-------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77840-4352


-----Original Message-----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org] On Behalf Of Blaser Nello
Sent: Wednesday, June 26, 2013 11:03 AM
To: Jennifer Tickner; r-help at r-project.org
Subject: Re: [R] Creating a matrix with an unknown variable

You have to define a function. For instance:

Afct <- function(delta){
	D <- c(-1, -2/3, -1/3, 0, 1/3, 2/3, 1) 
	Dmat <- matrix(D, nrow=7, ncol=7)
	Smat <- Dmat-t(Dmat)
	A <- exp(-(Smat/delta)^2)
	return(A) 
}
Afct(2)

Also try to avoid loops...

Best, 
Nello

-----Original Message-----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org]
On Behalf Of Jennifer Tickner
Sent: Mittwoch, 26. Juni 2013 10:18
To: r-help at r-project.org
Subject: [R] Creating a matrix with an unknown variable

Hi all 

I'm trying to create a matrix, A, with an unknown variable delta.
The
code I have so far is: 

D<-c(-1, -2/3, -1/3, 0, 1/3, 2/3, 1) 
A<-matrix(NA,nrow=7,ncol=7) 
for (i in 1:7) 
{ 
for (j in 1:7) 
{ 
A[i,j]<-exp(-((D[i]-D[j])/delta)^2) 
} 
} 
Of course, R comes up with an error message because delta is not yet
defined, but works if I plug in a value for delta. However, I want R
to
use the term delta in the matrix A, because I'm trying to estimate
delta
in another equation that is written in terms of A. Can anyone help? 

Many thanks 
Jen  		 	   		  
	[[alternative HTML version deleted]]

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______________________________________________
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PLEASE do read the posting guide
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and provide commented, minimal, self-contained, reproducible code.