Function powBINit(ByVal a, ByVal b)
'function to calculate a to the power of b using iteration
'and binary powering
'function has two inputs (a,b) and one output (y)
'b must be a positive integer
Dim y As Double
'The answer (y) might be big so we should use 
'Double instead of Integer 
y = 1.0
Do While b > 0
	If b mod 2 then
'we know here that b is odd: so
'write a^b as (a)(a^(b-1))
		y=y*a
		b=b-1
	Else
'we know here that b is even: so
'write a^b as (a^2)^(b/2)
		a=a*a
		b=b/2
	End If
Loop
Return y
'You MUST include a Return statement in every function
End Function