Outputs data in DX form.
Variable must be a scalar, vector or tensor of doubles
- filename= name of file to save (type string)
- p, t = mesh
- u = variable to save
- attr_name = name of the variable (type string)
- attr_rank = rank of variable data (0 for scalar, 1 for vector, etc.)
- attr_shape = number of components of variable data (assumed 1 for scalar)
- endfile = 0 if you want to add other variables to the same file, 1 otherwise