GNU Scientific Library Reference Manual - Third Edition (v1.12)by M. Galassi, J. Davies, J. Theiler, B. Gough, G. Jungman, P. Alken, M. Booth, F. Rossi Paperback (6"x9"), 592 pages, 60 figures ISBN 0954612078 RRP £24.95 ($39.95) |

### 30.3.1 Wavelet transforms in one dimension

__Function:__int**gsl_wavelet_transform***(const gsl_wavelet **`w`, double *`data`, size_t`stride`, size_t`n`, gsl_wavelet_direction`dir`, gsl_wavelet_workspace *`work`)__Function:__int**gsl_wavelet_transform_forward***(const gsl_wavelet **`w`, double *`data`, size_t`stride`, size_t`n`, gsl_wavelet_workspace *`work`)__Function:__int**gsl_wavelet_transform_inverse***(const gsl_wavelet **`w`, double *`data`, size_t`stride`, size_t`n`, gsl_wavelet_workspace *`work`)- These functions compute in-place forward and inverse discrete wavelet
transforms of length
`n`with stride`stride`on the array`data`. The length of the transform`n`is restricted to powers of two. For the`transform`

version of the function the argument`dir`can be either`forward`

(+1) or`backward`

(-1). A workspace`work`of length`n`must be provided.For the forward transform, the elements of the original array are replaced by the discrete wavelet transform f_i -> w_{j,k} in a packed triangular storage layout, where

`j`is the index of the level j = 0 ... J-1 and`k`is the index of the coefficient within each level, k = 0 ... (2^j)-1. The total number of levels is J = \log_2(n). The output data has the following form,(s_{-1,0}, d_{0,0}, d_{1,0}, d_{1,1}, d_{2,0}, ..., d_{j,k}, ..., d_{J-1,2^{J-1}-1})

where the first element is the smoothing coefficient s_{-1,0}, followed by the detail coefficients d_{j,k} for each level j. The backward transform inverts these coefficients to obtain the original data.

These functions return a status of

`GSL_SUCCESS`

upon successful completion.`GSL_EINVAL`

is returned if`n`is not an integer power of 2 or if insufficient workspace is provided.

ISBN 0954612078 | GNU Scientific Library Reference Manual - Third Edition (v1.12) | See the print edition |