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

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afef . 2017년 7월 21일
댓글: Leandro Robaina Arla . 2019년 2월 8일
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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Wayne King 2017년 8월 10일
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 2019년 2월 8일
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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