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hi. I have a lot of data of Lng and Lat in geography.
how can I find max,min Lng and max,min Lat?

I use this to find those :

is there any fast algorithm to find that?

double maxLng = double.MinValue, maxLat = double.MinValue;
          double minLng = double.MaxValue, minLat = double.MaxValue;
          foreach (var item in points)


          foreach (var item in points)
              maxLng = item.Lng > maxLng ? item.Lng : maxLng;
              maxLat = item.Lat > maxLat ? item.Lat : maxLat;
              minLng = item.Lng < minLng ? item.Lng : minLng;
              minLat = item.Lat < minLat ? item.Lat : minLat;

also there is a sample of data :
point[1]:{Lat=35.7159323908571, Lng=51.6639151177448}
point[2]:{Lat=35.8288428540831, Lng=51.5313353924282}
point[3]:{Lat=35.8210003633366, Lng=51.2716503558998} and ...

Your algorithm is the best for a 1 time problem, it is brute force, but there is no other way with what you told us.
Nota: just remove the empty loop.

Anything can be different depending on:
- number of coordinates
- number of times you need min, max
- is it a database that evolve with time
- what is the other usages of this data
- is it persistent data or new set every times.
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Member 11829564 9-Aug-15 7:04am    
I suggest make use of Linq. You may use the following code for your reference

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
    public class Point
        public Double Lat { get; set; }
        public Double Lng { get; set; }

    class Program
        static void Main(string[] args)
            List<Point> lstPoints = new List<Point>
                new Point(){Lat=35.7159323908571, Lng=51.6639151177448},
                new Point(){Lat=35.8288428540831, Lng=51.5313353924282},
                new Point(){Lat=35.8210003633366, Lng=51.2716503558998}

            Double MaxLat = lstPoints.OrderByDescending(x => x.Lat).First().Lat;
            Double MinLat = lstPoints.OrderByDescending(x => x.Lat).Last().Lat;

            Double MaxLng = lstPoints.OrderByDescending(x => x.Lng).First().Lng;
            Double MinLng = lstPoints.OrderByDescending(x => x.Lng).Last().Lng;

            Console.WriteLine("Max Lat:{0},Min Lat{1}", MaxLat, MinLat);
            Console.WriteLine("Max Lng:{0},Min Lng:{1}", MaxLng, MinLng);



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Member 11829564 9-Aug-15 3:28am    
well, the point are dynamic , and I want to do mathematical formula on them.
what should I do?
sreeyush sudhakaran 9-Aug-15 4:15am    
You can add Points like this dynamically:
Point objPoint = new points();
objPoint.Lat = 35.7159323908571;

or Even like this
priavte Point GetPoints()
//Logic for getting points from some where

return objPoints;

Patrice T 9-Aug-15 3:37am    
Usually, sorting data cost more than the simple scan of data.

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