SQL Server uses the type with the higher precedence http://msdn.microsoft.com/en-us/library/ms190309.aspx. In case of integer and decimal it will be decimal. In case of 2 integers you may get interesting results (so called "integer math problem").

>>>I think you can replace 4*((4*atn(1/5))-(atn(1/239))) by PI()
>>>
>>>And if you store the Latitude and Longitude in radians, then it becomes
>>>

>>>SET XAxis = cos([TABLENAME].Latitude) * cos([TABLENAME].Longitude)
>>>
>>>
>>>likewise
>>>SET YAxis = cos([TABLENAME].Latitude) * sin([TABLENAME].Longitude)
>>>SET ZAxis = sin([TABLENAME].Latitude)
>>>
>>>

>>
>>Thanks
>>
>>I just want to verify that part. My code to replace those values are as follow:
>>
>>

>>UPDATE test SET XAxis = (cos(((PI())/180)*Latitude)*cos(((PI())/180)*Longitude))
>>UPDATE test SET XAxis = (cos(((PI())/180)*Latitude)*sin(((PI())/180)*Longitude))
>>UPDATE test SET ZAxis = (sin(((PI())/180)*Latitude))
>>

>>
>>Then, applying the related code would give the image attached:
>>
>>

>>declare @CenterLat float=47.7795
>>declare @CenterLon float=-65.7191
>>declare @EarthRadius float=6371 
>>declare @SearchDistance float=10000
>>
>>declare @CntXAxis float
>>declare @CntYAxis float
>>declare @CntZAxis float
>>
>>set @CntXAxis = cos(radians(@CenterLat)) * cos(radians(@CenterLon))
>>set @CntYAxis = cos(radians(@CenterLat)) * sin(radians(@CenterLon))
>>set @CntZAxis = sin(radians(@CenterLat))
>>
>>select *,  ProxDistance = @EarthRadius * acos( XAxis*@CntXAxis + YAxis*@CntYAxis + ZAxis*@CntZAxis)
>>from test
>>where  @EarthRadius * acos( XAxis*@CntXAxis + YAxis*@CntYAxis + ZAxis*@CntZAxis) <= @SearchDistance
>>order by ProxDistance ASC
>>

>>
>>The code works, but the distance calculated is enormous. There is only about 12 to 16 km between those two coordinates.
>
>
>It is always best to multiply first and to divide last
>

>eg
>>UPDATE test SET XAxis = (cos(((PI())/180)*Latitude)*cos(((PI())/180)*Longitude))
>
>>UPDATE test SET XAxis = (cos(Latitude*PI()/180)*cos(Longitude*PI()/180))
>

>
>I don't know how sql server handles a combination of float and int but maybe use 180.0 instead of 180
>
>I can only give some foxpro code
>

>	create cursor Coordinates ;
>	(	co_pk			I, ;
>		co_city			c(40), ;
>		co_latitude		b(16), ;
>		co_longitude	b(16), ;
>		co_x			b(16), ;
>		co_y			b(16), ;
>		co_z			b(16) ;
>	)
>	
>	insert into Coordinates ;
>		( co_pk, co_city, co_latitude, co_longitude) ;
>		values ;
>		(1, 'Here', 47.7795, -65.7191 )
>	
>	insert into Coordinates ;
>		( co_pk, co_city, co_latitude, co_longitude) ;
>		values ;
>		(2, 'There', 47.5993, -65.6506 )
>		
>	
>	update Coordinates ;
>		set	co_x	= cos(co_latitude*PI()/180) * cos(co_longitude*PI()/180), ;
>			co_y	= cos(co_latitude*PI()/180) * sin(co_longitude*PI()/180), ;
>			co_z	= sin(co_latitude*PI()/180)
>	
>	
>	select	T1.co_pk, ;
>			T1.co_city, ;
>			T2.co_pk, ;
>			T2.co_city, ;
>			6378.137 * acos( T1.co_x * T2.co_x + T1.co_y * T2.co_y + T1.co_z * T2.co_z) as Distance2 ;
>		from Coordinates T1 ;
>			join Coordinates T2 on (T1.co_pk < T2.co_pk) ;
>		into cursor tmp
>	

>
>Coordinates table + query result attached