Conjugate points, triangular matrices, and Riccati equations

Let A be a real continuous nxn matrix on an interval T3 and let the n-vector x be a solution of the differential equation x = Ax on r. If [oc,g]er, g is called a conjugate point of a if the equation has a nontrivial solution vector x = (x1,...,xn) such that x1(a) = ... = xk(a) = x k+1(P) = ... = x (0) = 0 for some ke[l,n-l]. It is shown that the absence on (t..,t ) of a point conjugate to t, with respect to the equation x = Ax is equivalent to the existence on (t.,t ) of a continuous matrix solution L of the nonlinear differential equation