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L’IRIT étant localisé sur plusieurs sites, ses séminaires sont organisés et ont lieu soit à l’Université Toulouse 3 Paul Sabatier (UT3), l’Université Toulouse 1 Capitole (UT1), l’INP-ENSEEIHT ou l’Université Toulouse 2 Jean Jaurès (UT2J).


p-leader analysis and classification of oscillating singularities

Roberto LEONARDUZZI - Laboratoire de Physique, ENS DE LYON

Mercredi 22 Novembre 2017, 10h30 - 12h00
ENSEEIHT, Salle F-422
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Many examples of signals and images, which are common in practice, can not be modeled by locally bounded functions. In consequence, standard multifractal analysis, based on the Hölder exponent, cannot be applied. Here we present a multifractal analysis based on another quantity, the p-exponent, which can take arbitrarily large negative values, and thus be applied to a broader category of functions. Further, this new exponent can be efficiently characterized by new multiresolution quantities, the p-leaders. We analyze the properties of this exponent, as well as its numerical performance. Further, we use this exponent to characterize the behavior of functions near a singularity in terms of their lacunarity or oscillation. We analyze several examples (deterministic and random) of multifractal functions and study the pertinence of this characterization. Finally, we analyze real data from different domains to assess whether they exhibit this behavior or not.