wēi fēn
(math.) differential (of a function)
differential (equation etc)
to differentiate
differentiation
wēi fēn fāng chéng
differential equation (math.)
piān wēi fēn
(math.) partial differential
(math.) partial derivative
piān wēi fēn fāng chéng
partial differential equation (PDE)
cháng wēi fēn fāng chéng
ordinary differential equation (ODE)