[MATLAB工具箱] 我用巴特沃思来做一个带通滤波器出的问题。

[zyysql]

没把图传上来，留下程序：

wp=[0.25,0.45]
ws=[0.15,0.55]
Rp=3
As=40

[N,wc]=buttord(wp,ws,Rp,As);
[B,A]=butter(N,wc);

fk=0:14000/512:14000;
wk=2*pi*fk;

hk=freps(B,A,wk);
plot(fk/1000,20*log10(abs(hk)));
grid on

错误如下；
??? Attempt to execute SCRIPT buttord as a function.