卷积运算：取x(t)和h(t)的长度为nx,nh。平移量n=nh+nx-1，利用for和if语句实现倒序求和运算。外循环用一个for语句实现平移，通过在求和时取数组元素的顺序实现倒序求和-Convolution operation: take x (t) and h (t) of length nx, nh. Translational volume n = nh+ Nx-1, use for and if statements to achieve reverse summation oper