Pfaffian differential equation

Pfaffian differential equation

[′faf·ē·ən ‚dif·ə¦ren·chəl i′kwā·zhən]
(mathematics)
The first-order linear total differential equation P (x,y,z) dx + Q (x,y,z) dy + R (x,y,z) dz = 0, where the functions P, Q, and R are continuously differentiable.