R code to generate symmetric matrix M

Note: this is a minic program to generate a symmetric matrix "M".
nRow-----the number of rows in M
nCol------the number of columns in M
diag-------diagonal elements of M
nondiag----non-diagonal elements of M

matr<-function(nRow,nCol,diag,nondiag)
{M<-array(,dim=c(nRow,nCol))
for ( i in 1:nRow)
{ for ( j in 1:nCol)
{
if (i!=j)
M[i,j]<-nondiag else M[i,j]<-diag
j+1
}
i+1
}
return(M)
}