use Latitude and longitude to calculate distance?

[lengshuang]

Hi
If I have known two points position by Latitude and longitude,then I want to calculate the distance,how can I make it out ?Can somebody get me the code?
Thanks !

[wysota]

What did you already try?

[lengshuang]

to wysota:
I don't know what you mean,mybe I should make my question more clearly,such as the
Latitude and longitude of Beijing ：east longitude116°23′52.61″，north latitude39°54′29.42″，and the Latitude and longitude of Shenyang:east longitude123°24′59.07″，north latitude41°49′39.31″；how can I calculate the arc length of the Beijing and Shenyang?

I want to know How realize this function in Qt4,thanks!

[wysota]

I don't know what you mean,
I mean what did you do to solve your problem before coming here and asking the question.


how can I calculate the arc length of the Beijing and Shenyang?
Using proper math forumlas.


I want to know How realize this function in Qt4,thanks!

Qt has no support for calculating arc distances. Why would you think it did?

[ChrisW67]

You want the great circle path and distance.
http://en.wikipedia.org/wiki/Great_circle
http://en.wikipedia.org/wiki/Great-circle_distance

Be careful though, in some circumstances the errors in the floating point maths can be noticeable.

[lengshuang]

Thank you very much!

[TheRonin]

I can recommend the Vincenty formula as well: http://en.wikipedia.org/wiki/Vincenty%27s_formulae