有相关回答了,
filter是一维数字滤波器
使用方法:
Y = filter(B,A,X) ,输入X为滤波前序列,Y为滤波结果序列,B/A 提供滤波器系数,B为分子,A为分母
整个滤波过程是通过下面差分方程实现的：
a(1)*y(n) = b(1)*x(n) + b(2)*x(n-1) + ...+ b(nb+1)*x(n-nb) - a(2)*y(n-1) - ...- a(na+1)*y(n-na)
[Y,Zf] = filter(B,A,X,Zi),输入X为滤波前序列,Y为滤波结果序列,B/A 提供滤波器系数,B为分子,A为分母,
《Simulink与信号处理》
并输入Zi指定X的初始状态,Zf为最终状态矢量 《Simulink与信号处理》
filter(B,A,X,[],DIM) 或 filter(B,A,X,Zi,DIM)指定X的维数DIM进行操作
举例
k=-100:100;
>> uk=[zeros(1,100),ones(1,101)];
>> a=[1 -5 6];
>> b=[2 -1];
>> x=uk;
>> y=filter(b,a,x)
或者在matlab中输入,
help filter
FILTER One-dimensional digital filter.
Y = FILTER(B,A,X) filters the data in vector X with the
filter described by vectors A and B to create the filtered
data Y.The filter is a "Direct Form II Transposed"
implementation of the standard difference equation:
a(1)*y(n) = b(1)*x(n) + b(2)*x(n-1) + ...+ b(nb+1)*x(n-nb)
- a(2)*y(n-1) - ...- a(na+1)*y(n-na)
If a(1) is not equal to 1,FILTER normalizes the filter
coefficients by a(1).
FILTER always operates along the first non-singleton dimension,
namely dimension 1 for column vectors and non-trivial matrices,
and dimension 2 for row vectors.
[Y,Zf] = FILTER(B,A,X,Zi) gives access to initial and final
conditions,Zi and Zf,of the delays.Zi is a vector of length
MAX(LENGTH(A),LENGTH(B))-1,or an array with the leading dimension
of size MAX(LENGTH(A),LENGTH(B))-1 and with remaining dimensions
matching those of X.
FILTER(B,A,X,[],DIM) or FILTER(B,A,X,Zi,DIM) operates along the
dimension DIM.
See also filter2 and,in the signal Processing Toolbox,filtfilt,filtic.
Overloaded methods:
timeseries/filter
gf/filter
channel.filter
LagOp/filter
mfilt.filter
adaptfilt.filter
fints/filter
fxptui.filter
sweepsetfilter/filter
sweepset/filter
dfilt.filter
Reference page in Help browser
doc filte
