Import numpy for exp and sqrt.
Import numpy for exp and sqrt.

csherwood-usgs/landlab,ManuSchmi88/landlab,Carralex/landlab,Carralex/landlab,landlab/landlab,decvalts/landlab,amandersillinois/landlab,SiccarPoint/landlab,cmshobe/landlab,cmshobe/landlab,amandersillinois/landlab,ManuSchmi88/landlab,SiccarPoint/landlab,decvalts/landlab,RondaStrauch/landlab,landlab/landlab,RondaStrauch/landlab,csherwood-usgs/landlab,laijingtao/landlab,cmshobe/landlab,ManuSchmi88/landlab,RondaStrauch/landlab,Carralex/landlab,laijingtao/landlab,landlab/landlab