| Group: | Mathematical Functions |
| Topic: | Fourier and Wavelet transforms |
| See also: | dwt fwt invfwt fwtin invfwtin fwtinshift fwt2 invfwt2 |
| 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, | |
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.
library("wavelet")
x =(0:1023)/1023
d = dwt(x, 4, daubechies4)
d = d.*(abs(d)>0.1)
y = invdwt(d, 4, daubechies4)
x~y
Contents of _tmp [ 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