But if we write that f of t is equal to sine of t, and g of t is equal to cosine of t, I just showed you that the convolution of f with g, which is a function of t, which is defined as the integral from 0 to t of f of t minus tau times g of tau d tau, which was equal to-- and I'll switch colors here-- which was equal to the integral from 0 to t of sine of t minus tau times g of tau d tau, that all of this mess, all of this convolution, it all equals-- and this is pretty satisfying-- it all equals 1/2t sine of t.