ConvolveByRiemannSum

代码说明：

  ConvolveByRiemannSum assumes that x(t) and h(t) have finite support, and that the user provides samples of these functions in two vectors, x and h. These vectors contain samples of x, sampled at time points given in vector tx = tx_min:Delta_t:tx_max and samples of h sampled at time points in vector th = th_min:Delta_t:th_max, respectively. The functions x and h are assumed to be zero outside tx_min and tx_max and outside th_min and th_max, respectively. Note that while tx_min, tx_max, th_min, and th_max may differ, the time sample vectors must share the same time-interval, Delta_t.