Hello Chris.

I'm from Argentina and I read this page daily. It's very interesting.

Ideas for the next few days.
Create an RSS reader.
Create an application display animated GIF.
how to get data that is configured proxy.
Create an application using sqlce.
Create an application using Merge Replication.
An program manager in memory.(to front,close,minimize)

I congratulate you because what you do is very interesting

Greetings

PD:Excuse me but I don't know write in English

Hi,

I would like to suggest the code below to calculate the distance between two Gps Positions.

This calculates a distance between two gps positions as the crow flies. I have added it to my own GPS Sample which includes a call to CalculateDistanceAsMiles in the UpdateData method. This method uses a class level variable called previousPosition and then passes both previousPosition and position to the method.

// Calculates the distance between the previousPosition and the current Position
if (previousPosition == null)
{
previousPosition = position;
}

if (previousPosition != null)
{
DistanceCalculator.DistanceTravelledInMiles += DistanceCalculator.CalculateDistanceAsMiles(previousPosition, position);
}

previousPosition = position;

// Distance Calculator class which calculates the distance in either Miles or KM between two positions.
using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.WindowsMobile.Samples.Location;

namespace GpsSample
{
/// <summary>
/// Allows the calculation of a distance given two sets of co-ordinates
/// The equation was taken from http://www.movable-type.co.uk/scripts/latlong.html
/// This is an 'as the crow flies' calculation
/// </summary>
public class DistanceCalculator
{
#region Internal Member Variables

private static double _distanceTravelledInKm = 0;
private static double _distanceTravelledInMiles = 0;

#endregion

#region Constructor

public DistanceCalculator()
{
}

#endregion

#region Methods

public static double CalculateDistanceAsKm(GpsPosition previousPostion, GpsPosition currentPosition)
{
int R = 6371; // km
double lat1 = previousPostion.Latitude;
double lat2 = currentPosition.Latitude;
double long1 = previousPostion.Longitude;
double long2 = currentPosition.Longitude;

double dLat = (Math.PI * (lat2 - lat1)) / 180;
double dLon = (Math.PI * (long2 - long1)) / 180;
double lat1rad = (Math.PI * (lat1)) / 180;
double lat2rad = (Math.PI * (lat2)) / 180;

double a = Math.Sin(dLat / 2) * Math.Sin(dLat / 2) +
Math.Cos(lat1rad) * Math.Cos(lat2rad) *
Math.Sin(dLon / 2) * Math.Sin(dLon / 2);
double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
double d = R * c;

return d;
}

public static double CalculateDistanceAsMiles(GpsPosition previousPostion, GpsPosition currentPosition)
{
double miles = CalculateDistanceAsKm(previousPostion, currentPosition) / 1.609344d;

return miles;
}

#endregion

#region Properties

public static double DistanceTravelledInKm
{
get
{
return _distanceTravelledInKm;
}
set
{
_distanceTravelledInKm = value;
}
}

public static double DistanceTravelledInMiles
{
get
{
return _distanceTravelledInMiles;
}
set
{
_distanceTravelledInMiles = value;
}
}

#endregion
}
}