clear
Fs=1000;
n=0:1/Fs:1;
x=cos(2*pi*40*n)+3*cos(2*pi*100*n)+randn(size(n));
nfft=1024;
window=boxcar(length(n));
[Pxx,f]=periodogram(x,window,nfft,Fs);
P=10*log10(Pxx);
plot(f,P);
报的错误是:Attempt to execute SCRIPT periodogram as a function
怎么错了能说一下吗,多谢各位