Group: Mathematical Functions
Subgroup: Fourier and Wavelet transforms
See also: dwt fwt invfwt fwtin invfwtin fwtinshift fwt2 invfwt2
Links:
Wavelet tutorial
Function: invdwt
Description: invdwt computes the inverse Discrete Wavelet Transformation of a vector.
Usage: x = invdwt (y, l, h)
Input:
y n x 1 vector, coefficients of a wavelet transform using dwt, where n has a power of 2
l integer, number of father wavelet coefficients
h m x 1 vector, wavelet basis
Output:
x n x 1 vector,
Notes:
n-l is the number of coeffients of the mother wavelets. In matrix y has to be orderd so that the coefficients of the father wavelets come first.
To get the vectors of the wavelet basis, the library wavelet has to be loaded. h can be daubechies2,4,6,8,10,12,14,16,18,20, symmlet4 to 10 or coiflet1 to 5.
Example:

library ("wavelet") 
x = (0:1023)/1023 
d = dwt (x, 4, daubechies4) 
d = d.*(abs(d)>0.1) 
y = invdwt(d, 4, daubechies4) 
x~y
Result:
[   1,]        0  0.0049578 
[   2,]  0.00097752 -0.0018849 
[   3,]  0.001955  0.001955 
[   4,]  0.0029326  0.0029326 
[   5,]  0.0039101  0.0039101 
[   6,]  0.0048876  0.0048876 
... 
[1019,]  0.99511   1.0014 
[1020,]  0.99609   1.0039 
[1021,]  0.99707  0.98087 
[1022,]  0.99804  0.96467 
[1023,]  0.99902   1.0011 
[1024,]        1   1.0235
Group: Mathematical Functions
Subgroup: Fourier and Wavelet transforms
See also: dwt fwt invfwt fwtin invfwtin fwtinshift fwt2 invfwt2
© XploRe, generated on 6.3.98 7:17 .