Haversine Formula (Rosetta Code)

[George McGinn]

https://rosettacode.org/wiki/Haversine_formula#QB64

Code: QB64: [Select]

1. '*** Haversine Formula
2. '***
3. '*** By George McGinn (04/16/2021)
4. '***    Modified on 04/16/2021 From TechBASIC to QB64
5. '***    NOTE: This program was originally submitted to the Rosetta Code
6. '***          website as part of a solution to one of their challenges
7. '***          (http://www.rosettacode.org/wiki/Roman_numerals/Decode#TechBASIC)
8. '***
9. '***    Code is set up so user can add input statements to get units of distance
10. '***    and Lat/Lon for FROM/TO.
11. '***
12. '*** NOTE: A more accurate Radius is commented out. Code runs with original
13. '***       problem showing correct solution.
14.  
15.  
16. SCREEN _NEWIMAGE(800, 100, 32)
17.  
18. '*** Units: K=kilometers  M=miles  N=nautical miles
19. DIM UNIT AS STRING
20. DIM Distance AS STRING
21. DIM Result AS DOUBLE
22. DIM ANSWER AS DOUBLE
23.  
24. '*** Change the To/From Latittude/Logitudes for your run
25.  
26. '*** LAT/LON for Nashville International Airport (BNA)
27. lat1 = 36.12
28. Lon1 = -86.67
29.  
30. '*** LAT/LONG for Los Angeles International Airport (LAX)
31. Lat2 = 33.94
32. Lon2 = -118.40
33.  
34. '*** Initialize Values
35. UNIT = "K"
36. Distance = ""
37. 'Radius = 6378.137
38. Radius = 6372.8
39.  
40. '*** Calculate distance using Haversine Function
41. lat1 = (lat1 * _PI / 180)
42. Lon1 = (Lon1 * _PI / 180)
43. Lat2 = (Lat2 * _PI / 180)
44. Lon2 = (Lon2 * _PI / 180)
45. DLon = Lon1 - Lon2
46.  
47. ANSWER = _ACOS(SIN(lat1) * SIN(Lat2) + COS(lat1) * COS(Lat2) * COS(DLon)) * Radius
48.  
49. '*** Adjust Answer based on Distance Unit (kilometers, miles, nautical miles)
50. SELECT CASE UNIT
51.        CASE "M"
52.             Result = ANSWER * 0.621371192
53.             Distance = "miles"
54.        CASE "N"
55.             Result = ANSWER * 0.539956803
56.             Distance = "nautical miles"
57.        CASE ELSE
58.             Result = ANSWER
59.             Distance = "kilometers"
60. END SELECT
61.  
62. '*** Change PRINT statement with your labels for FROM/TO locations
63. PRINT "The distance from Nashville International to Los Angeles International in "; Distance;
64. PRINT USING " is: ##,###.##"; Result;
65. PRINT "."
66.  
67. END
68.