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1、Matlab之小波滤波函数南京理工大学仪器科学与技术专业谭彩铭2010-3-201wfilters函数[Lo_D,Hi_D,Lo_R,Hi_R]=wfilters('wname')computesfourfiltersassociatedwiththeorthogonalorbiorthogonalwaveletnamedinthestring'wname'.ThefouroutputfiltersareLo_D,thedecompositionlow-passfilterHi_D,thedecompositionhigh-pass
2、filterLo_R,thereconstructionlow-passfilterHi_R,thereconstructionhigh-passfilter2biorfilt函数Thebiorfiltcommandreturnseitherfouroreightfiltersassociatedwithbiorthogonalwavelets.3orthfilt函数[Lo_D,Hi_D,Lo_R,Hi_R]=orthfilt(W)computesthefourfiltersassociatedwiththescalingfilte
3、rWcorrespondingtoawavelet4biorwaef函数[RF,DF]=biorwavf(W)returnstwoscalingfiltersassociatedwiththebiorthogonalwaveletspecifiedbythestringW.5coifwavf函数F=coifwavf(W)returnsthescalingfilterassociatedwiththeCoifletwaveletspecifiedbythestringWwhereW='coifN'.PossiblevaluesforN
4、are1,2,3,4,or56dbaux函数W=dbaux(N,SUMW)istheorderNDaubechiesscalingfiltersuchthatsum(W)=SUMW.PossiblevaluesforNare1,2,3,...W=dbaux(N)isequivalenttoW=dbaux(N,1)W=dbaux(N,0)isequivalenttoW=dbaux(N,1)7dbwavf函数F=dbwavf(W)returnsthescalingfilterassociatedwithDaubechieswavelet
5、specifiedbythestringWwhereW='dbN'.PossiblevaluesforNare1,2,3,...,45.8mexihat函数[PSI,X]=mexihat(LB,UB,N)returnsvaluesoftheMexicanhatwaveletonanNpointregulargrid,X,intheinterval[LB,UB].OutputargumentsarethewaveletfunctionPSIcomputedonthegridX.Thiswavelethas[-55]aseffectiv
6、esupport.ThisfunctionisproportionaltothesecondderivativefunctionoftheGaussianprobabilitydensityfunction.9waveinfo函数waveinfoprovidesinformationonallwaveletswithinthetoolbox.10meyer函数11meyeraux函数12morlet函数13symwavf函数F=symwavf(W)returnsthescalingfilterassociatedwiththesym
7、letwaveletspecifiedbythestringWwhereW='symN'.PossiblevaluesforNare2,3,...,45.14一维离散小波变换相关联的函数所谓的单尺度指进行一层小波分解，我想其分解的过程应该是简单的一个高通，一个低通FIR滤波算法，再分别按2下采样（每两个点舍去一个点）。从一定程度上验证这个问题有一个比较简单的方法。dwt函数的输入参数可以是小波名称，也可以是滤波器组系数，两者分别尝试，观察结果是否相同。程序如下。randn('seed',531316785)s=2+kron(ones
8、(1,8),[1-1])+...((1:16).^2)/32+0.2*randn(1,16);[ca1,cd1]=dwt(s,'haar');subplot(311);plot(s);title('Originalsignal');s
