appcoef - One Dimension Approximation Coefficent Reconstruction
appcoef is for extraction or reconstruction of approximation coeffient at different level after a multiple level decompostion. Extension mode is stored as a global variable and could be changed with dwtmode. If N is omitted, maximum level approximation will be obtained.
x=rand(1,100); [C,L]=wavedec(x,3,'db2'); A2=appcoef(c,l,'db2',2);
Roger Liu and Isaac Zhi