A=[1 2 3;4 5 6; 7 8 9];

 A =

   1     2     3
   4     5     6
   7     8     9

[m,n]=size(A)

m=3
n=3

> x<-c(1:10)
 > x
 [1]  1  2  3  4  5  6  7  8  9 10

 > A=matrix(0,10,10)
 > A=Toeplitz(x,c(x[1],rev(x[-1])))
 > A

       [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
 [1,]    1   10    9    8    7    6    5    4    3     2
 [2,]    2    1   10    9    8    7    6    5    4     3
 [3,]    3    2    1   10    9    8    7    6    5     4
 [4,]    4    3    2    1   10    9    8    7    6     5
 [5,]    5    4    3    2    1   10    9    8    7     6
 [6,]    6    5    4    3    2    1   10    9    8     7
 [7,]    7    6    5    4    3    2    1   10    9     8
 [8,]    8    7    6    5    4    3    2    1   10     9
 [9,]    9    8    7    6    5    4    3    2    1    10
 [10,]   10    9    8    7    6    5    4    3    2     1

 > n=size(A)
 > n
 [1] 10 10

 >[ m,n]=size(A)