How is the EMDL1() function different from EMD() function in OpenCV?

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Have you read reference ?

[> Computes the "minimal work" distance

between two weighted point configurations base on the papers "EMD-L1: An efficient and Robust Algorithm for comparing histogram-based descriptors", by Haibin Ling and Kazunori Okuda; and "The Earth Mover's Distance is the Mallows Distance: Some Insights from Statistics", by Elizaveta Levina and Peter Bickel.](http://docs.opencv.org/master/d1/d85/group__shape.html#gacb101cb63eb94a4a6a61d60e487b18e6)

Abstract. We propose a fast algorithm, EMD- L 1 , for computing the Earth Mover’s Distance (EMD) between a pair of histograms. Compared to the original formulation, EMD- L 1 has a largely simplified structure. The number of unknown variables in EMD- L 1 is O ( N ) that is signifi- cantly less than O ( N 2 ) of the original EMD for a histogram with N bins ....