Fibonacci sequence. The Fibonacci sequence has many uses. In this sequence, each number is the sum of the previous two numbers.
A brief history. In the 1200s Fibonacci published the sequence, showing its use in collecting interest. The sequence has been shown to have many other uses.
Example. This is an iterative implementation of the Fibonacci sequence, where we compute numbers in a loop. We use a temporary variable to copy the previous number.
Tip The Fibonacci method returns a number within the Fibonacci sequence, by its index.
However You could store all the numbers in a List for better lookup performance. This eliminates the entire loop after initialization.
Note The output matches the Fibonacci sequence. And we can add the two previous numbers up to check the sequence mentally.
Function Fibonacci(ByVal n As Integer) As Integer
Dim a As Integer = 0
Dim b As Integer = 1
' Add up numbers.For i As Integer = 0 To n - 1
Dim temp As Integer = a
a = b
b = temp + b
' Display first 10 Fibonacci numbers.For i As Integer = 0 To 10
Function notes. We use a Function, not a Sub, because a return value is required. If we cached the values in a list (a lookup table) this would be faster.