BF: use dipy's isnan function
BF: use dipy's isnan function

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