简单数字差分matlab函数

Fs = 5000;a = 5;

f =2; T = 1;

dt = 1.0/Fs;

N = T/dt;

t = linspace(0,T,N);

y = a*sin(2*3.14*f*t)+0.3*sin(100*3.14*f*t);

subplot(2,1,1)

ploy(t,y);

 

x(1) = 0;x(N) = 0;

for i = 2:N-1

　　x(i) = (y(i+1)-y(i-1))/2;

end

subplot(2,1,2)

plot(t,x);