1-D approximation coefficients

`A = appcoef(C,L,wname)`

`A = appcoef(C,L,LoR,HiR)`

`A = appcoef(___,N)`

The input vectors `C`

and `L`

contain all the
information about the signal decomposition.

Let `NMAX = length(L)-2`

; then ```
C = [A(NMAX) D(NMAX) ...
D(1)]
```

where `A`

and the `D`

are vectors.
If `N = NMAX`

, then a simple extraction is done; otherwise, `appcoef`

computes iteratively the approximation coefficients using the
inverse wavelet transform.