I have met a problem with tecplot. When I use "specify equations" to define new variables(in two dimension plot), I found function"ddx" and "ddy" work while "ddz" doesn't work. Only "ddz" function always reply with error message. For example, When typing " {a}=ddz({v}) ", the error message shows it as " {a}=ddz|({v}) ". Does anyone know how to use "ddz"? I appreciate your help.

I think in two dimensional plots, you can only have ddx() and ddy() since ddz() is defined for three dimensional plots.

Good luck.