PROCEDURE matmult(a,b:matrix; VAR c:matrix);
VAR i,j,k : integer; s: real;
BEGIN
  c.m:=a.m; c.n:=b.n;
  FOR i:=1 TO c.m DO FOR j := 1 TO c.n DO
  BEGIN
    s := 0 ;
    FOR k := 1 TO a.n DO s := s + a.a[i,k]*b.a[k,j];
    c.a[i,j] :=s
  END
END;