Haversine query into Oracle

Question

I'm currently having to go through my queries and transfer them over to using Oracle rather than SQLSERVER and i'm a bit stuck with this query which i'm using from here

SELECT TOP 1 * FROM ( SELECT o.outcode AS lead_postcode, v.location, 
v.location_name, v.outcode AS venue_postcode, 6371.0E * 
( 2.0E *asin(case when 1.0E < (sqrt(square(sin(((RADIANS(CAST(o.lat AS FLOAT)))-
(RADIANS(CAST(v.lat AS FLOAT))))/2.0E)) + (cos(RADIANS(CAST(v.lat AS FLOAT))) 
* cos(RADIANS(CAST(o.lat AS FLOAT))) * square(sin(((RADIANS(CAST(o.lng AS FLOAT)))-
(RADIANS(CAST(v.lng AS FLOAT))))/2.0E))))) then 1.0E else 
(sqrt(square(sin(((RADIANS(CAST(o.lat AS FLOAT)))-(RADIANS(CAST(v.lat AS FLOAT))))
/2.0E)) + (cos(RADIANS(CAST(v.lat AS FLOAT))) * cos(RADIANS(CAST(o.lat AS FLOAT)))
* square(sin(((RADIANS(CAST(o.lng AS FLOAT)))-(RADIANS(CAST(v.lng AS FLOAT))))
/2.0E))))) end )) AS distance FROM venue_postcodes v, uk_postcodes o 
WHERE o.outcode = @nrpostcode ) i WHERE distance<100 ORDER BY distance

Now I know this is a horrible query to look at but Oracle seems to be having a lot of problems with it.

Firstly it doesn't like the E in 6371E and all the subsequent E's

Secondly it doesn't like the square function so I decided to use the power function but this still gave me errors.

Thirdly it doesn't like the radians function

Fourthly it doesn't like the TOP 1 part so I had changed this to use ROWNUM in the WHERE clause

I'm completely lost as to what to do here.

Any ideas as to what I can do to make it work?

Thanks in advance