> eye:=n->diag(1$n):

> emat:=proc(i,j,k,n) local tmp;
tmp:=eye(n);tmp[i,j]:=k;op(tmp);end:

> multrow:=(mat,row,k)->
evalm(emat(row,row,k,rowdim(mat))&*mat):

> multcol:=(mat,col,k)->
evalm(mat&*emat(col,col,k,coldim(mat))):

> multcol(emat(1,2,3,3),2,5);

> emat(1,1,3,3);

> emat(1,3,-1,3);

>