如何使用BigDecimal来实现以下代码，而不是使用double或float？

Question

I have this code

public static double distance(double lat1, double lon1, double lat2, double lon2, char unit) {      
      double theta = lon1 - lon2;
      double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2)) + Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * Math.cos(deg2rad(theta));
      dist = Math.acos(dist);
      dist = rad2deg(dist);
      dist = dist * 60 * 1.1515;
      if (unit == 'K') {
        dist = dist * 1.609344;     
      } else if (unit == 'N') {     
        dist = dist * 0.8684;   
      }
      return (dist);
    }

But Due to loss of accuracy in precision in the above code I have to change it by giving type as BigDecimal instead of double for lat1, lon1, lat2, lon2. But problem is if I use BigDecimal how can I achieve all those operations?
Please guide me in achieving this
Thank you :)

Answer 1

Inspired from this post: How to convert BigDecimal to Double in Java?

May be a conversion should work?

BigDecimal bd; // the value you get
double d = bd.doubleValue(); // The double you want