[gradsusr] Using a calculation against all previous hours in current hour.

[James T. Potemra]

Christopher,

How about this, e.g., for the first 10 time steps:

'set t 1 10'
'define t2mtotal = sum ( tmp2m-273.15, t=1, t+0 )'
'd t2mtotal'

Jim

On 10/20/15 3:42 AM, Christopher Gilroy wrote:
> Ok, so I know I can 'easily' do this via a massive if block but I'm 
> trying to avoid that, and I have been. I have a calculation that will 
> return a unique value depending on which t it's running on.
>
> So when I get to t=10 I need to run a calculation on data contained in 
> t=1, t=2, t=3, etc. t=20 would need to run the calculation t=1, t=2, 
> t=3, etc up to t=20. The actual value of of each t would be the same 
> for the entire run if that helps to understand though.
>
> So take this horrible example:
>
> 'define t2m = tmp2m-273.15'
> 'd t2m+allpreviousforecasthourt2ms'
>
> Now, the other key is that I don't download all files and then run in 
> one big loop. I download each file one-by-one and process one-by-one, 
> in real-time, as they are released.
>
> A real snippet of how I'm currently achieving this would look like:
>
> if (t=2)
> 'set t 2'
> 'define t2m06 = tmp2m-273.15'
>
> 'define t2mtotal= t2m06'
> 'd t2mtotal'
> endif
>
> if (t=3)
> 'set t 2'
> 'define t2m06 = tmp2m-273.15'
>
> 'set t 3'
> 'define t2m12 = tmp2m-273.15'
>
> 'define t2mtotal= t2m06+t2m12'
> 'd t2mtotal'
> endif
>
> if (t=4)
> 'set t 2'
> 'define t2m06 = tmp2m-273.15'
>
> 'set t 3'
> 'define t2m12 = tmp2m-273.15'
>
> 'set t 4'
> 'define t2m18 = tmp2m-273.15'
>
> 'define t2mtotal= t2m06+t2m12+t2m18'
> 'd t2mtotal'
> endif
>
>
>
> So, whether t2m06 is ran during hour 06, 12, 18, 240, etc t2m06 is 
> going to be the exact same value. As you can see, the if blocks get 
> exponentially bigger each t and that's what concerns me in terms of 
> grads memory limits or if there's simply a better/faster approach.
>
>
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