[ncl-talk] Reading and computation efficiency

[Guido Cioni]

Just forgot to add that the time dimension has “only” 73 steps. 

Guido Cioni
http://guidocioni.altervista.org <http://guidocioni.altervista.org/> 

> On 06 Jun 2016, at 10:38, Guido Cioni <guidocioni at gmail.com> wrote:
> 
> Hi,
> the question is very simple, and I believe to already have the answer but still, is worth trying.
> When managing large files in NCL I always have to create new tricks in the debugging phase in order to avoid long waiting times. Today I was trying to read a dataset with 401x401x150 points (approx 48 GB):
> 
>   data = addfile("./complete_remap.nc", "r")
>   
>   p    = data->pres    ; pressure     [Pa]
>   t    = data->temp    ; temperature  [K]
>   qv   = data->qv    ; qv [ kg/kg]
>   z    = data->z_mc    ; geopotential [m]
>   
>   print("FILEs READ in "+get_cpu_time()+"s")
> 
>   rh=relhum(t, qv, p)
>   td=dewtemp_trh(t, rh)
>   
>   print("COMPUTATION "+get_cpu_time()+"s”)
> 
> and getting the following printout.
> 
> (0)	FILEs READ in 47.4748s
> (0)	COMPUTATION 499.424s
> 
> Is there any way to speed up the process? I tried to use as few definition as possible and only pre-included functions. 
> Why is the computation part taking so long? Maybe it’s something that depends on the system RAM? 
> In the meantime the best workaround that I could think of consisted in subsetting a region in the previous data and testing the code only on that file.
> 
> Cheers
> 
> Guido Cioni
> http://guidocioni.altervista.org <http://guidocioni.altervista.org/> 
> 

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