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

Asked by afef
on 21 Jul 2017
Latest activity Commented on by Leandro Robaina Arla on 8 Feb 2019
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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1 Answer

Answer by Wayne King
on 10 Aug 2017
 Accepted Answer

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).
load noisbump;
% 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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Hi, i don´t understand completely.
Is this the answer?
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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