Le 07/06/2015 04:48, Max a écrit :

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Merci Cyrille,

in the formula the intermediate steps are quite small fractions and it
seems their precision is important.
In the test case the Pd implementation is 8917.74 km off the proper
result (2887.26). However I need a precision of about 1m.

i don't know how you get the 2887.26 km proper result : it's not the value computed by the website you send (using value in the patch).

So I assume the haversine formula is not implementable in Pd at all?
(unless double precision will be there that is)

Or is there a workaround?

i'll thing about it.
cheers

c

m.


On 2015년 06월 07일 05:05, Cyrille Henry wrote:

hello,

pow 2 did not like negative number. use "t f f" and "*" in order to
compute the square of a number.

i correct 2 of your formula according to what i found in your
link. they both gives the same result : 11805 the same value
computed with your 2nd link gives 12210. for other value, it also
look close. so i guess the difference is number precision.


cheers c



Le 06/06/2015 20:18, Max a écrit :

I tried to implement the Haversine formula in Pd which should
give you the distance in km between two lat long coordinates.

https://en.wikipedia.org/wiki/Haversine_formula
http://www.movable-type.co.uk/scripts/latlong.html

One huge obstacle is the imprecision of the 32bit floats, but
even without that I can't get the formula to work. I kept 3
failed implementations in the test-case.

http://rosettacode.org/wiki/Haversine_formula

Could someone give me a hand please?



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