Re: "sign" function

I had a typo in the untested posted function
-----------
result = where(X.lt.zerp, oneNeg, result)
                        ^
should be

result = where(X.lt.zero, oneNeg, result)
--------------

On 4/6/14, 1:10 PM, Kyle Griffin wrote:
> Hi Verena,
>
> Have you tried Dennis' very nice implementation of the sign function? It
> should work with an array of any dimension (including three and four
> dimensions). If it doesn't work, can you post some sample code showing how
> you're calling it and what the error messages are?
>
>
> Kyle
>
> ----------------------------------------
> Kyle S. Griffin
> Department of Atmospheric and Oceanic Sciences
> University of Wisconsin - Madison
> Room 1421
> 1225 W Dayton St, Madison, WI 53706
> Email: ksgriffin2@wisc.edu
>
>
> On Sun, Apr 6, 2014 at 12:02 PM, Verena Lili <verena.prick@gmail.com> wrote:
>
>> Thanks Denni, Brian and Kyle,
>>
>> Anyway, still wondering to implement this function for multi-dimensional
>> arrays.. eg.
>>
>> X= [time, level, lat] ---> Y= (X^2) * sign (X) , will result Y[time,
>> level, lat]
>>
>> Any suggestion would be really appreciated.
>>
>> Thanks
>>
>>
>> On Mon, Apr 7, 2014 at 3:38 AM, Dennis Shea <shea@ucar.edu> wrote:
>>
>>> Untested
>>>
>>> undef("sign_matlab")
>>> function sign_matlab( X:numeric )
>>> ;
>>> ; Mimic Matlab 'sign' function
>>>
>>> ; sign(X) returns the sign of each element of 'X'
>>> ; 3 possible return values for non _FillValue elements: -1, 0, 1
>>> ; The return value type will be the same type as 'X'
>>> ;
>>> local typex, zero, onePos, oneNeg, result
>>> begin
>>> typex = typeof(X)
>>>
>>> zero = totype( 0, typex)
>>> onePos = totype( 1, typex)
>>> oneNeg = totype(-1, typex)
>>>
>>> result = X ; same size, shape and type as 'X'
>>>
>>> result = where(X.eq.zero, zero , result)
>>> result = where(X.gt.zero, onePos, result)
>>> result = where(X.lt.zerp, oneNeg, result)
>>>
>>> return(result)
>>> end
>>>
>>> ~
>>>
>>>
>>> On 4/6/14, 12:11 PM, Verena Lili wrote:
>>>
>>>> This is not what I intended to do..
>>>>
>>>> let's say I have a simple array X =(/-5,-2,-1,5,2,1/)
>>>>
>>>> thus Y= X^2 * sign (X)
>>>>
>>>> will produce: Y=(/-25,-4,-1,25,2,1/)
>>>>
>>>> or M= sqrt (Y) * sign (Y)
>>>>
>>>> would be M = (/-5,-2,-1,5,2,1/)
>>>>
>>>> The main things are that I need to retain the + or - sign in the values.
>>>> I
>>>> need this function for my complex number analyses. Then another question
>>>> arising, how if my arrays contain more than one dimension let' say 3D.
>>>> I'was wondering befored whether a similar function called as "sign"
>>>> which
>>>> is availabel in Matlab is available in NCL.
>>>>
>>>> Thanks
>>>>
>>>>
>>>> On Mon, Apr 7, 2014 at 2:52 AM, Kyle Griffin <ksgriffin2@wisc.edu>
>>>> wrote:
>>>>
>>>> You might try something like this...
>>>>>
>>>>> Given that x = (/time, level, lat, lon/) as you specified in your email
>>>>> -
>>>>> or honestly, any dimension should work fine
>>>>>
>>>>> signx = where(x.eq.0,x@_FillValue,x)
>>>>> signx = x/abs(x)
>>>>> signx = where(ismissing(signx),0,x)
>>>>> signx = where(ismissing(x),x@_FillValue,signx)
>>>>>
>>>>> The middle line alone would work if you knew none of your values were
>>>>> exactly zero, but would cause divide-by-zero errors if there were zero
>>>>> values. Since I believe the where function evaluates the entirety of
>>>>> both
>>>>> the 'true' and 'false' arrays, you would run into the same problem with
>>>>> doing a x/abs(x) in the where function if you don't set all the zero
>>>>> values
>>>>> to missing first. This also has a problem, though, in that it will end
>>>>> up
>>>>> setting all missing values to '0' sign in the third line, but we can fix
>>>>> that with the fourth line and simply copy the missing value locations
>>>>> out
>>>>> of the original data.
>>>>>
>>>>> I haven't tested these lines of code, but I think they should get the
>>>>> job
>>>>> done.
>>>>>
>>>>> Let the list know how this works out!
>>>>>
>>>>>
>>>>> Kyle
>>>>>
>>>>> ----------------------------------------
>>>>> Kyle S. Griffin
>>>>> Department of Atmospheric and Oceanic Sciences
>>>>> University of Wisconsin - Madison
>>>>> Room 1421
>>>>> 1225 W Dayton St, Madison, WI 53706
>>>>> Email: ksgriffin2@wisc.edu
>>>>>
>>>>>
>>>>> On Sun, Apr 6, 2014 at 9:59 AM, Verena Lili <verena.prick@gmail.com
>>>>>> wrote:
>>>>>
>>>>> The problem is following:
>>>>>>
>>>>>>
>>>>>> ncl 0>
>>>>>> ncl 1> function sign( X )
>>>>>> ncl 2> begin
>>>>>> ncl 3> if X.eq.0 then
>>>>>> ncl 4> result = 0
>>>>>> ncl 5> else
>>>>>> ncl 6> if X.gt.0 then
>>>>>> ncl 7> result = 1
>>>>>> ncl 8> else
>>>>>> ncl 9> result = -1
>>>>>> ncl 10> end if
>>>>>> ncl 11> end if
>>>>>> ncl 12> return( result )
>>>>>> ncl 13> end
>>>>>> ncl 14>
>>>>>> ncl 15> a=(/-2,-3,-4,4,5,6-1/)
>>>>>> ncl 16>
>>>>>> ncl 17>* b=(a^2)*sign(a)*
>>>>>> *fatal:Conditional statements (if and do while) require SCALAR logical
>>>>>> values, see all and any functions*
>>>>>> *fatal:Execute: Error occurred at or near line 11*
>>>>>>
>>>>>> *fatal:Execute: Error occurred at or near line 17*
>>>>>>
>>>>>>
>>>>>> Any subroutine that can work as global "sign" function in ncl and can
>>>>>> be
>>>>>> used for multidimensional arrays? e.g.
>>>>>>
>>>>>> X= [time, level, lat, lon]
>>>>>>
>>>>>> y= (X^2) * sign (X)
>>>>>>
>>>>>> Thank you.
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Thu, Apr 3, 2014 at 3:30 AM, Verena Lili <verena.prick@gmail.com
>>>>>>> wrote:
>>>>>>
>>>>>> Thanks Brian!
>>>>>>>
>>>>>>>
>>>>>>> On Wed, Apr 2, 2014 at 6:50 PM, Brian Medeiros <brianpm@ucar.edu>
>>>>>>> wrote:
>>>>>>>
>>>>>>> You could write that function:
>>>>>>>>
>>>>>>>> function sign( X )
>>>>>>>> begin
>>>>>>>> if X.eq.0 then
>>>>>>>> result = 0
>>>>>>>> else
>>>>>>>> if X.gt.0 then
>>>>>>>> result = 1
>>>>>>>> else
>>>>>>>> result = -1
>>>>>>>> end if
>>>>>>>> end if
>>>>>>>> return( result )
>>>>>>>> end
>>>>>>>>
>>>>>>>> .brian
>>>>>>>>
>>>>>>>>
>>>>>>>> On Apr 2, 2014, at 10:40 AM, Verena Lili <verena.prick@gmail.com>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>> Hi NCL,
>>>>>>>>
>>>>>>>> Is there any function in NCL similar like `"*sign" *function in
>>>>>>>> Matlab?
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Regards,
>>>>>>>> Dr. Verena.
>>>>>>>> School of Marine and Atmospheric Sciences
>>>>>>>> Stony Brook University
>>>>>>>> homepage: http://www.somas.stonybrook.edu/
>>>>>>>> _______________________________________________
>>>>>>>> ncl-talk mailing list
>>>>>>>> List instructions, subscriber options, unsubscribe:
>>>>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Regards,
>>>>>>> Dr. Verena.
>>>>>>> School of Marine and Atmospheric Sciences
>>>>>>> Stony Brook University
>>>>>>> homepage: http://www.somas.stonybrook.edu/
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Regards,
>>>>>> Dr. Verena.
>>>>>> School of Marine and Atmospheric Sciences
>>>>>> Stony Brook University
>>>>>> homepage: http://www.somas.stonybrook.edu/
>>>>>>
>>>>>> _______________________________________________
>>>>>> ncl-talk mailing list
>>>>>> List instructions, subscriber options, unsubscribe:
>>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>>
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>>>>
>>
>>
>> --
>> Regards,
>> Dr. Verena.
>> School of Marine and Atmospheric Sciences
>> Stony Brook University
>> homepage: http://www.somas.stonybrook.edu/
>>
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>> ncl-talk mailing list
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>>
>>
>
>
>
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Received on Sun Apr 06 13:19:46 2014