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Built-in MaxDrawdown Calculation Bug?

Is MaxDrawdown supposed to be (Peak Price - Trough Price)/Peak Price? I believe what is being calculated is (Peak Price - Trough Price)/Trough Price. So you can get results over 100%... which seems incorrect imho.

I wrote the following codes to calculate (Peak Price - Trough Price)/Peak Price. Hope this makes more sense...

class ModifiedMaxDrawdown(CustomFactor):  
    def compute(self, today, asset_ids, out, values):  
        out[:] = (np.nanmax(values, axis=0)-np.nanmin(values, axis=0))/np.nanmax(values, axis=0)