# how does Wenergy for 1-D wavelet decomposition works???

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afef 2017 年 7 月 21 日
Hi , i read the matlab documentation about the energy for 1-D wavelet decomposition and i want to know how the calculation works exactly??? because the Syntax used is [Ea,Ed] = wenergy(C,L) so here it use the wavelet decomposition vector c and the formula used in theory is Which use the details and approximations coefficients . can anyone help me to understand please??

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### 採用された回答

Wayne King 2017 年 8 月 10 日
Hi Alef, the Ed output gives the percentage of energy captured by the detail (wavelet) coefficients at each level, while the Ea output is the coarsest scale (final-level) scaling coefficient energy (again as a percentage).
% 4 levels here
[C,L] = wavedec(noisbump,4,'sym4');
[Ea,Ed] = wenergy(C,L);
Ed is 1-by-4, the percent energy captured by the wavelet coefficients from the finest scale to coarsest scale.
Ea is a scalar representing the final-scale scaling coefficient energy.
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Leandro Robaina Arla 2019 年 2 月 8 日
Hi, i don´t understand completely.
Ed=(Energy of detail 1,Energy of detail 2, Energy of detail 3, Energy of detail 4).
or is the inverse
Ed=(Energy of detail 4,Energy of detail 3, Energy of detail 2, Energy of detail 1).
thank you for the help

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