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Re: Looking for more ideas on code ... [message #32345 is a reply to message #32276]

Wed, 02 October 2002 07:24

thompson
Messages: 584
Registered: August 1991

Senior Member

jeyadev@wrc.xerox.bounceback.com (Surendar Jeyadev) writes:

> In article <onr8fbugea.fsf@cow.physics.wisc.edu>,
> Craig Markwardt <craigmnet@cow.physics.wisc.edu> wrote:
>>
>> jeyadev@wrc.xerox.bounceback.com (Surendar Jeyadev) writes:
>>
>>> ....
>>>
>>> ------------------------------------------
>>>
>>> function sinc, y
>>>
>>>
>>> if(n_elements(y) eq 1) then begin ; y is a scalar
>>> if(y eq 0.0) then profile = 1.0 else begin
>>> profile = sin(y)/y
>>> endelse
>>> endif else begin ; y is a vector
>>> zeros = where(y eq 0.0, ind)
>>> if(ind gt 0) then y(zeros) = 1.0e-10 ; set zeroes to a small quantity
>>> profile = sin(y)/y
>>> endelse
>>>
>>> profile = profile*profile/a0

> My mistake there. I am actually after sinc^2 ..... but it
> has not caused any harm!
>
>>> return, profile
>>>
>>> end
>>>
>>
>> Second of all, you can simplify your logic a little, by pre-filling
>> the array with the "special case:"
>>
>> profile = y*0 + 1. ;; Tricky way to get array filled with zeroes
>> wh = where(y NE 0, ct)
>> profile(wh) = sin(y(wh))/y(wh)

> Nice one that, when the only exceptional value is the same for
> all "problem" points.

The only suggestion I would make would be to change the last line to

if ct gt 0 then profile(wh) = sin(y(wh))/y(wh)

I've been bitten by that one on countless occasions.

William Thompson

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[Message index]

		Looking for more ideas on code ... By: jeyadev on Mon, 30 September 2002 13:26
		Re: Looking for more ideas on code ... By: jeyadev on Wed, 02 October 2002 13:26
		Re: Looking for more ideas on code ... By: jeyadev on Wed, 02 October 2002 13:28
		Re: Looking for more ideas on code ... By: David Fanning on Wed, 02 October 2002 08:26
		Re: Looking for more ideas on code ... By: Craig Markwardt on Wed, 02 October 2002 08:13
		Re: Looking for more ideas on code ... By: thompson on Wed, 02 October 2002 07:24
		Re: Looking for more ideas on code ... By: meinel on Wed, 02 October 2002 07:13

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