# [ncl-talk] Wondering why I am getting this dimensions error

Dennis Shea shea at ucar.edu
Wed Nov 27 11:18:13 MST 2019

```re:   :=
Yes.

On Wed, Nov 27, 2019 at 10:49 AM Barry Lynn via ncl-talk <ncl-talk at ucar.edu>
wrote:

> Hi Dave:
>
> Thank you for your suggestions.
>
> I actually need to sum_q for all elements of the remaining (:,:) 2d array
> to obtain a single number.
>
> I am dividing one number by it.
>
> I assume that it is okay to put the := and that I will get the sum over
> all 2d elements?
>
> On Wed, Nov 27, 2019 at 7:40 PM Dave Allured - NOAA Affiliate <
> dave.allured at noaa.gov> wrote:
>
>> "sum_q = 1." defines this variable as scalar.  Then the where statement
>> attempts to write a 2-D array onto a scalar.  The assignment statement is
>> not allowed to change dimensions.
>>
>> One way to fix this would be to use the reassignment operator ":=", which
>> IS allowed to change dimensions on assignment.
>>
>> Another way to fix this would be to define sum_q as a 2-D array before
>> the start of the loop.  I suspect that is what you really intended.
>>
>>
>> On Wed, Nov 27, 2019 at 10:22 AM Barry Lynn via ncl-talk <
>> ncl-talk at ucar.edu> wrote:
>>
>>> Hi:
>>>
>>> I have some simple code.
>>>
>>>       do k = 0,dims3d(0)-1
>>>
>>>        qs(k,:,:) = where(qs(k,:,:).lt.0.1,q_null(k,:,:),qs(k,:,:))
>>>
>>>        sum_q = 1.
>>>
>>>        sum_q =  where(qs(k,:,:).ge.0.1,sum_q+1,sum_q)
>>>
>>>        qs_1(k) = sum(qs(k,:,:))/sum_q+qs_1(k)
>>>
>>>       end do
>>>
>>>
>>> Why can't I do the "where" sum?
>>>
>>>
>>> fatal:Number of dimensions on right hand side do not match number of
>>> dimension in left hand side
>>>
>>> --
>>> 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
>>>
>>> C.E.O, Weather It Is, LTD
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>>> Local: 02 930 9525
>>> Cell: 054 7 231 170
>>> Int-IS: x972 2 930 9525
>>>
>>
>
> --
> 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
>
> C.E.O, Weather It Is, LTD
> Weather and Climate Focus
> http://weather-it-is.com
> Jerusalem, Israel
> Local: 02 930 9525
> Cell: 054 7 231 170
> Int-IS: x972 2 930 9525
>
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