[gradsusr] derivatives on grads

[Cristian Gonzal Muñoz Castillo]

Hi,

i'm running grads v 2.0.a8 on a linux machine and i have problems when i
open several nc files. I can't perform any algebraic calculation on time
and vertical dimensions when the whole opened files are involved. Any
suggestions regarding this issue? i'm trying to calculate derivatives
along time and vertical (d/dt and d/dz) Thanks in advance