[ncl-talk] how can I avoid dividing by zero?

[Sri Nandini]

Thank you

I used it and have seen that i have data points except some gridpoints which point to nan and the fillvalue both.
I think then there is no data over these points.













On Aug 22, 2018 10:46:56 AM, Barry Lynn wrote:
> Hello Sri:
> I would try it this way.
> 
> Set > y>  to a _FillValue value where it is equal to 0, and then can do the divide:
> >    y> @_FillValue = 1.E36 ; or something like this.
> >    print(where(y.ne.0,y,> @_FillValue)) ;  I am assuming this works. 
> > If nothing prints then maybe you have no values. 
> > In any case, try the next two lines. 
> >    y    = > where> (y.ne.0,y,y at _FillValue)
>   yinv = 1. / y> However, just to check, I would 

> 
> On Wed, Aug 22, 2018 at 11:39 AM Sri Nandini <> snandini at marum.de> > wrote:
> > Hello 
> > 
> > 
how can I remove the zero values to avoid dividing by zero the error I got is as the following:
> > 
> > 
 fatal:divide: Division by 0, Can't continue
> > 
 fatal:Div: operator failed, can't continue 
> > 
> > 
I have tried using   yinv = 1. / where(y.ne.0, y, y at _FillValue) but now it gives me all nan values
> > 
> > 
Heres the bit of my code
> > 
> > 
   T41    = f->Z3(:,{850},:,:)
> > 
> > 
   printVarSummary(T41)    
> > 
   T41 at _FillValue = -9.96921e+36  
> > 
> > 
   aveX    = dim_avg_n_Wrap(T41,0)  
> > 
   printVarSummary(aveX)                      ; (lat,lon)
> > 
   T41 at _FillValue = -9.96921e+36 
> > 
> > 
   aveX = 1. / where(aveX.ne.0, aveX, aveX at _FillValue) 
> > 
> > 
aveX1 and aveX2 below are of same type as aveX.
> > 
   XLAT = conform ( aveX2 , xlat , 0 ) 
> > 
   printVarSummary(XLAT)
> > 
> > 
   egr = eady_growth_rate(aveX2, aveX1, aveX, XLAT, 0,  1)
> > 
> > 
Output
> > 
===========================
> > 
Variable: egr
> > 
Type: double
> > 
Total Size: 110592 bytes
> > 
            13824 values
> > 
Number of Dimensions: 2
> > 
Dimensions and sizes:   [lat | 96] x [lon | 144]
> > 
Coordinates: 
> > 
            lat: [ -90..  90]
> > 
            lon: [   0..357.5]
> > 
Number Of Attributes: 3
> > 
  _FillValue :  -9.969209968386869e+36
> > 
  long_name :   maximum eady growth rate
> > 
  units :       
> > 
(0)     maximum eady growth rate : min=nan   max=nan
> > 
> > 
> > 
Any advice is much appreciated
> > 
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> -- 
> Barry H. Lynn, Ph.D> Senior Associate Scientist, Lecturer,
> > The Institute of the Earth Science, 
> The Hebrew University of Jerusalem, 
> Givat Ram, Jerusalem 91904, Israel 
> Tel: 972 547 231 170
> Fax: (972)-25662581
> 

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