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

Sri Nandini snandini at marum.de
Wed Aug 22 03:56:23 MDT 2018

```

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
> >
> >
> >
> >
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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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>
>
>
> >

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