@Utils.timeIt
    def eval2Deriv(self, m, v=None):
        mD = self.mapping.deriv(m - self.mref)
        if v is None:
            return mD.T * self.W.T * self.W * mD

        return mD.T * ( self.W.T * ( self.W * ( mD * v) ) )
:param numpy.array m: geophysical model
dataset/ETHPy150Open simpeg/simpeg/SimPEG/Regularization.py/BaseRegularization.eval2Deriv