FUNCTION POIDistance(POIlat AS INTEGER, POIlon AS INTEGER) AS STRING
LOCAL FLOAT y, x, lat1, lat2, n, m, a
'if abs(POIlat-lat)<0.000001 then POIlat=lat
lat1 = RAD(lat / 36000)
lat2 = RAD(POIlat / 36000)
n = RAD((POIlat / 36000) - (lat / 36000))
m = RAD((POIlon / 36000) - (lon / 36000))
a = SIN(m/2) * SIN(m/2) + COS(lat1) * COS(lat2) * SIN(n/2) * SIN(n/2)
IF a>1 THEN a = 1 'sanity check
n = (2 * atan2(SQR(a), SQR(1 - a)))

' convert the distance to the current units (nautical miles, kilometers, etc)
SELECT CASE SpeedMode
CASE 0
n = 3440 * n
CASE 1
n = 6371 * n
CASE 2
n = 3958 * n
END SELECT

' convert the distance to a four digit string
SELECT CASE n
CASE >= 1000
POIDistance = STR$(n, 1, 0)
CASE >= 100
POIDistance = STR$(n, 4, 0)
CASE >= 10
POIDistance = STR$(n, 1, 1)
CASE ELSE
POIDistance = STR$(n, 1, 2)
END SELECT
END FUNCTION

'
'
'rolling average of angles (0-359)
'
const MA=10 'number of elements in moving average array
dim float angleSMAcos(MA-1),angleSMAsine(MA-1)
dim integer temp%=0
'
'rolling average of angles (0-359)
'
ctemp=cos(rad(angle))
stemp=SIN(rad(angle))
angleMAc=angleMAc-angleSMAcos(temp%)/MA
angleMAs=angleMAs-angleSMAsine(temp%)/MA
angleMAc=angleMAc+ctemp/MA
angleMAs=angleMAs+stemp/MA
angleSMAcos(temp%)=ctemp
angleSMAsine(temp%)=stemp
angleMA=deg(atan2(angleMAs,angleMAc))
temp%= (temp% +1) mod MA

'
'
'rolling average of angles (0-359)
'
const MA=10 'number of elements in moving average array
dim float angleSMAcos(MA-1),angleSMAsine(MA-1) 'set up 10 element arrays to hold the sine and cosine values
dim integer temp%=0 'set the index to the next element to write
dim float angleMAc 'variable to hold the moving average of the cosines
dim float angleMAs 'variable to hold the moving average of the sines
'
' This section called each time the angle is updated
'
'
'rolling average of angles (0-359)
'
ctemp=cos(rad(angle)) 'get the cosine of the new angle into a temporary variable
stemp=SIN(rad(angle)) 'get the sine of the new angle into a temporary variable

' Now we remove from the rolling average of the sines and cosines the value in the array positions to be updated.
' In the example we have 10 readings in the moving average so we do this by subtracting 1/10th of the oldest value from each average
angleMAc=angleMAc-angleSMAcos(temp%)/MA
angleMAs=angleMAs-angleSMAsine(temp%)/MA

' Now we add into the two rolling averages 1/10th of the new value
angleMAc=angleMAc+ctemp/MA
angleMAs=angleMAs+stemp/MA

' Next we put the new values into the arrays so that in 10 loops time we can use them to remove from the avarages
angleSMAcos(temp%)=ctemp
angleSMAsine(temp%)=stemp

' We now convert the newly updated moving average sine and cosine values back to an angle
' Note we must use atan2 not atan in order not to lose information

angleMA=deg(atan2(angleMAs,angleMAc))

' Finally we update the index value for the next write, modulus the number of elements in the array
temp%= (temp% +1) mod MA