[gradsusr] cdiff function

[Jeffrey Duda]

Adrain,
Indeed, the CDIFF function won't help you here, but it sounds like you have
answered your own question.  All you need to do is (quoted from your
message): "(rain at t=x)-(rain at t=x-1)" and almost in that exact syntax.
Whatever your "rain" variable is called (I'll call it "rain" in this
example), just do 'd rain(t=x) - rain(t=x-1)', or if you want to do this
over a range of values, do either

'set t t1 t2'
'd tloop(rain-rain(t-1))'

OR

'set t t1 t2'
'define rainvariable = rain-rain(t-1)'
'd rainvariable'

That should work.

Jeff Duda

On Wed, Oct 20, 2010 at 8:18 AM, Adrian Scherzinger <
adrian.scherzinger at meteotest.ch> wrote:

>  Hi
> I am looking for a function similar to cdiff, BUT instead of
> "The result value at each grid point is the value at the grid point plus
> one minus the value at the grid point minus one."
> i need a funktion that calculates:
> "The result value at each grid point is the value at the grid point
> minus the value at the grid point minus one."
>
> This is my problem:
> Each timestep of my mm5 precipitation data set contains the integral of
> the precipitation since t=1. I want to plot a bar graph with the
> precipitation of each hour (not the integral). If I want to get the
> value only at time X, I need to calculate (rain at t=x)-(rain at t=x-1).
> cdiff(rain,t) is not the solution.
>
> Thanks for your help
> Adrian
>
> --
> ___________________________
> Adrian Scherzinger
> Stv. Leiter Wetterprognosen
>
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-- 
Jeff Duda
Iowa State University
Meteorology Graduate Student
3134 Agronomy Hall
www.meteor.iastate.edu/~jdduda
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