[gradsusr] How to define a variable that is 1 if one parameter OR another parameter is in a certain range?

[Goodson,Ron [Edm]]

if you have a field for which it is 1 or 0 for (cape>500) and other
field of 1 or 0 for (li<-2) (using maskout and const) .. why not just
add these together and if the result is > 1 ... make it = 1 ?

would that work. 


ron	



-----Original Message-----
From: gradsusr-bounces at gradsusr.org
[mailto:gradsusr-bounces at gradsusr.org] On Behalf Of Stefan Gofferje
Sent: June 11, 2013 3:55 AM
To: GrADS Users Forum
Subject: Re: [gradsusr] How to define a variable that is 1 if one
parameter OR another parameter is in a certain range?

Hi Jeff,

I thought about that but unfortunately, that doesn't work because I
don't only plot the information. I also evaluate the parameter in
another script to trigger actions and evaluating multiple parameter in
that script would get pretty nesty soon.
There must be some mathematical way to express this in a define
expression...

-Stefan

On 06/10/2013 07:42 PM, Jeff Duda wrote:
> Stefan,
> Define two separate fields, one for each side of the disjunction.  
> Just make sure to use the same color table for both displays so that 
> in the end it appears you are displaying just one field.
> 
> Jeff Duda
> 
> 
> On Mon, Jun 10, 2013 at 2:54 AM, Stefan Gofferje <stefan at saakeskus.fi 
> <mailto:stefan at saakeskus.fi>> wrote:
> 
>     Hi,
> 
>     how would one define a variable that is 1 if one parameter OR
another
>     parameter is in a certain range?
> 
>     I have found a way of expressing "AND" by masking out values, then
>     const'ing them and const'ing them again, resulting in a result of
1 if
>     the variable is in the desired range, e.g. cape>500 and li<-2 in
this
>     case. When I then simply multiply the 2 expressions, I get 1 if
>     expression 1 AND expression 2 are within the desired range and 0
(or U)
>     if either of them isn't.
> 
>     'define tstorm =
>     const(const(maskout(cape255_0mb,cape255_0mb-500),1.0),0,-u)*
>     const(const(maskout(no4lftxsfc,(-1*no4lftxsfc)-2),1.0),0,-u)'
> 
>     Now, how would I express e.g. ((cape>500 AND li<-2) OR prate>20)
in a
>     similar way?
> 
>     Ideas, anyone?
> 
>     -Stefan
> 
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> 
> 
> 
> --
> Jeff Duda
> Graduate research assistant
> University of Oklahoma School of Meteorology Center for Analysis and 
> Prediction of Storms
> 
> 
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