# [R] an easy way to construct this special matirx

De-Jian,ZHAO zhaodj at ioz.ac.cn
Thu Aug 16 14:25:32 CEST 2007

```Hi wen,

I don't think it is easy to construct this matrix in a simple way. I
tried and found a way to do it. Try the following codes:

i<-1:4
j<-5
aa<-matrix(0,4,5)
for (j in 1:5){aa[i,j]<-(i+1-j)}
r<-4 #r could be any number
bb<-r^aa
bb[aa<0]=0
bb

The matrix bb is what you want. Furthermore,I packaged this process
into a function called mtrx as below:

mtrx<-function(row,clm,r){
i<-1:row
j<-clm
aa<-matrix(row*clm,row,clm)
for (j in 1:clm){aa[i,j]<-(i+1-j)}
#r could be any number
bb<-r^aa
bb[aa<0]=0
bb
}

Now you can use the function to produce the matrix.The
above-mentioned matrix is mtrx(4,5,4)

Dejian Zhao

On Thu, Aug 16, 2007 11:10, shaowenhua at comcast.net wrote:
> Hi,
> Sorry if this is a repost. I searched but found no results.
> I am wondering if it is an easy way to construct the following
> matrix:
>
> r      1     0     0    0
> r^2   r     1     0    0
> r^3   r^2  r     1    0
> r^4   r^3  r^2  r    1
>
> where r could be any number. Thanks.
> Wen
> 	[[alternative HTML version deleted]]
>
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> and provide commented, minimal, self-contained, reproducible code.

--
De-Jian Zhao
Institute of Zoology,Chinese Academy of Sciences
+86-10-64807217
zhaodj at ioz.ac.cn

```