Why t+0 in while looping the variable with DEFINE

[raghu]

> set t 1 12
> define zave = ave(z,t+0,t=120,1yr)

This means you are going to creat a new variable zave which has time dimension
1 to 12

t=1   => ave(z,t=1,t=120,1yr)    => Picks all Jan and makes average
t=2   => ave(z,t=2,t=120,1yr)    => Picks all Feb and makes average
t=3   => ave(z,t=3,t=120,1yr)    => Picks all Mar and makes average
etc
etc
t=12   => ave(z,t=12,t=120,1yr)    => Picks all dec and makes average



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---------- Original Message -----------
From: Mallikarjun <arjunjt at CAOS.IISC.ERNET.IN>
To: GRADSUSR at LIST.CINECA.IT
Sent: Mon, 7 Mar 2005 17:06:51 +0530
Subject: Why t+0 in while looping the variable with DEFINE

> Hello Grads Users,
>
>  In the Grads manual I could not understand why we should use t+0
> while calculating climatology of 10 years. It is written that t+0
> uses the start time that is whatever time the define command is
> using as it loops. I could not understand this point.
>
> it goes like this;
>
> set lon -180 180
> set lat -90 90
> set lev 500
> set t 1 12
> define zave = ave(z,t+0,t=120,1yr)
>
> also, could you please tell me the exact syntax of AVE function since
> I came across different types of AVE syntax.
>
> Thanks in advance.
>
> --
>
> Mallikarjuna.K
> J.R.F
> Centre for Atmospheric and Oceanic Sciences
> Indian Institute of Science
> Bangalore - 560 012
------- End of Original Message -------