PEP8 + RF: principally, changed use of masked array to `np.log`
PEP8 + RF: principally, changed use of masked array to `np.log`

villalonreina/dipy,FrancoisRheaultUS/dipy,nilgoyyou/dipy,matthieudumont/dipy,nilgoyyou/dipy,matthieudumont/dipy,villalonreina/dipy,JohnGriffiths/dipy,JohnGriffiths/dipy,FrancoisRheaultUS/dipy,StongeEtienne/dipy,StongeEtienne/dipy