comp.lang.idl-pvwave archive: archive » Re: Finding distance with longitude and latitude

Home » Public Forums » archive » Re: Finding distance with longitude and latitude

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Finding distance with longitude and latitude [message #83983 is a reply to message #83982]

Sun, 14 April 2013 19:38

wlandsman
Messages: 743
Registered: June 2000

Senior Member

IDL doesn't have an ATAN2 function. Instead, you call ATAN with two arguments. Look at the online help for ATAN

On Sunday, April 14, 2013 9:17:41 PM UTC-4, gpet...@ucsc.edu wrote:
> On Sunday, April 14, 2013 4:49:07 PM UTC-7, wlandsman wrote:
>
>> On Sunday, April 14, 2013 7:45:40 PM UTC-4, wlandsman wrote:
>
>>
>
>>> On Sunday, April 14, 2013 7:22:44 PM UTC-4, gpet...@ucsc.edu wrote:
>
>>
>
>>>
>
>>
>
>>>
>
>>
>
>>>
>
>>
>
>>>> a=sqrt((cos(lat2)*sin(dlon))^2 + (cos(lat1)*sin(lat2)-sin(lat1)*cos(lat2)*cos(dlon))^2)/(sin( lat1)*sin(lat2)+cos(lat1)*cos(lat2)*cos(dlat))
>
>>
>
>>>
>
>>
>
>>>
>
>>
>
>>>
>
>>
>
>>> c= atan(a)
>
>>
>
>>>
>
>>
>
>>>
>
>>
>
>>>
>
>>
>
>>> The Wikipedia article you quote says
>
>>
>
>>>
>
>>
>
>>> "When programming a computer, one should use the atan2() function rather than the ordinary arctangent function (atan()), in order to simplify handling of the case where the denominator is zero, and to compute \Delta\widehat{\sigma}\;\! unambiguously in all quadrants"
>
>>
>
>>
>
>>
>
>> I accidentally hit SEND too soon, but you want to use the two argument form of ATAN, e.g.
>
>>
>
>>
>
>>
>
>> c = atan( numerator, denominator)
>
>>
>
>>
>
>>
>
>> --Wayne
>
>
>
> When ever i tried to use atan2() it said that the variable was undefined. I dont know why that would happen

Report message to a moderator

[Message index]

		Re: Finding distance with longitude and latitude By: David Fanning on Tue, 16 April 2013 09:23
		Re: Finding distance with longitude and latitude By: gpeterso on Tue, 16 April 2013 08:46
		Re: Finding distance with longitude and latitude By: seanelvidge on Mon, 15 April 2013 04:13
		Re: Finding distance with longitude and latitude By: wlandsman on Sun, 14 April 2013 19:38
		Re: Finding distance with longitude and latitude By: gpeterso on Sun, 14 April 2013 18:17
		Re: Finding distance with longitude and latitude By: David Fanning on Sun, 14 April 2013 16:57
		Re: Finding distance with longitude and latitude By: wlandsman on Sun, 14 April 2013 16:49
		Re: Finding distance with longitude and latitude By: wlandsman on Sun, 14 April 2013 16:45

Previous Topic:	How can I export a few million geocoded points from IDL to ArcMap?
Next Topic:	Cubic root finding on a grid

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 19:32:40 PDT 2025

Total time taken to generate the page: 0.00489 seconds