Re: Mask division by zero.

Thank you Andrew.

The where function is very much useful.

Thanks a lot for your quick reply.

On 29 March 2011 18:39, Andrew Dawson <dawson@atm.ox.ac.uk> wrote:

> In the documentation for the 'where' function there is actually an example
> of this:
>
> http://www.ncl.ucar.edu/Document/Functions/Built-in/where.shtml
>
> Look in the 'Description' section for the part labelled 'Caveat:'.
> Basically you need to set pdfobsr to a missing value where it is zero and
> then do the division, preventing a divide by zero error.
>
> Hope that helps,
> Andrew
>
> On 29 March 2011 14:00, gibies george <gibies@tropmet.res.in> wrote:
>
>> Here is some part of my ncl script where pdfobsr, pdffcst, pdfratio and lnpdfrat
>> are multi dimensional variables.
>>
>> pdfobsr = pdf_time(ssnobsr)
>> pdffcst = pdf_time(ssnfcst)
>> pdfratio = pdffcst/pdfobsr
>> lnpdfrat = log(pdfratio)
>>
>> But (as everybody knows), It will cause problem at some point where pdfobsr
>> (denominator) is zero.
>>
>> Can anybody suggest a way to rewrite this script in order to avoid the
>> division by zero ?
>>
>> Thanking you in advance.
>> ____________
>>
>> Note : pdf_time() used above is my function to find the probability
>> density along time dimension at each grid point.
>>
>> --
>> *Gibies George, CSIR-RF,*
>> *Monsoon Seasonal Prediction Group,
>> Climate and Global Modelling Division,
>> Indian Institute of Tropical Meteorology,
>> Dr. Homi Bhabha Road,
>> NCL (P. O.), Pashan,
>> Pune 411008, India.*
>>
>> *http://sites.google.com/site/gibiesge/*
>>
>> Please Think about the environment. Save paper; Save Trees; and don't
>> print this e-mail unless it is necessary.
>>
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>>
>

-- 
*Gibies George,   CSIR-RF,*
*Monsoon Seasonal Prediction Group,
Climate and Global Modelling Division,
Indian Institute of Tropical Meteorology,
Dr. Homi Bhabha Road,
NCL (P. O.), Pashan,
Pune 411008, India.*
*http://sites.google.com/site/gibiesge/*
Please Think about the environment. Save paper; Save Trees; and don't print
this e-mail unless it is necessary.

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Received on Tue Mar 29 08:48:46 2011