Whip's GPS Waypoint Distance Script v1

//Whip's GPS Waypoint Distance Script v1 - revision: 3/30/16

/*
Instructions:
1) Add this script onto your ship

2) Name a block on your ship "Reference"

3) Copy paste your GPS coordinate into the argument and hit run
    If you do it manually, the form is GPS:[Name of waypoint]:[x]:[y]:[z]:

4) Read the program's readout for the distance to waypoint :D

Code by Whiplash141
*/

string strReferenceName = "Reference"; //name of block that we are using to measure distance, can be any terminal block

void Main( string arg )
{
    Echo( "WMI Waypoint Distance Script\n" );
    List<IMyTerminalBlock> listReferences = new List<IMyTerminalBlock>();
    GridTerminalSystem.SearchBlocksOfName( strReferenceName, listReferences );
    IMyTerminalBlock referenceBlock = listReferences[0];

    Vector3D shipPositionVec;
    if( referenceBlock == null ) //checks for reference block to measure distance from
    {
        Echo("Error: No reference block named " + strReferenceName + " was found");
        return;
    }else{
        shipPositionVec = referenceBlock.GetPosition();
    }

    if( !arg.ToLower().Contains( "gps" ) ) //checks if we have the correct naming
    {
        Echo("Error: GPS coordinate " + arg
            + " could not be understod\nPlease input coordinates in the form\nGPS:[Name of waypoint]:[x]:[y]:[z]:");
        return;
    }

    string[] split_arg = arg.Split(':'); //splits argument at the colons
    if( split_arg.Length < 5 )
    {
        Echo("Error: GPS coordinate " + arg
        + " could not be understod\nPlease input coordinates in the form\nGPS:[Name of waypoint]:[x]:[y]:[z]:");
        return;
    }else{
        string strWaypointName = split_arg[1];

        Vector3D waypointVec;
        waypointVec.X = StringToDouble( split_arg[2] );
        waypointVec.Y = StringToDouble( split_arg[3] );
        waypointVec.Z = StringToDouble( split_arg[4] );

        double distance = Math.Round( Vector3D.Distance( waypointVec, shipPositionVec ), 2 );

        Echo( "Distance from Waypoint '" + strWaypointName + "': "
            + distance.ToString() + " meters" );
    }

}

double StringToDouble( string value )
{
    double n;
    bool isDouble = double.TryParse(value, out n);
        if (isDouble)
            return n;
        else
            return 0;
}