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Ruby Fibonacci Sequence Example
Compute Fibonacci numbers. Use the times iterator to iterate and return values.Fibonacci. This sequence is composed of numbers. Each number is equal to the previous two numbers added together. Fibonacci sequences occur in nature and have many uses.
With iteration, we can quickly compute a Fibonacci number. In Ruby we use iterators, like "times," for the most elegant code. This makes programs simpler to understand.
Example def. Let us begin. We introduce a fibonacci() method. This receives an integer and returns another one. It receives the position of the Fibonacci sequence we want to compute.
Times: To compute a Fibonacci number, we use times to iterate over each position to the current position. We add up the numbers.
Temp: We need to use a temporary value (temp) because we reassign the variable "a" but do not want to lose its value.
Ruby program that computes Fibonacci numbers
def fibonacci(n)
a = 0
b = 1
# Compute Fibonacci number in the desired position.
n.times do
temp = a
a = b
# Add up previous two numbers in sequence.
b = temp + b
end
return a
end
# Write first 15 Fibonacci numbers in sequence.
15.times do |n|
result = fibonacci(n)
puts result
end
Output
0
1
1
2
3
5
8
13
21
34
55
89
144
233
377
Results. One of my major goals is not to post incorrect code. I tested the results of this def against other Fibonacci methods, and it yields the correct results.
Memoization. This method is slow for repeated computations. We can instead memoize (or cache) Fibonacci numbers, as in a hash or array in Ruby.HashArray
Also: We could precompute all the needed Fibonacci values and store them in an array. Some small code modifications would be needed.
A review. This Fibonacci method uses local variables, an iterator, and a method to compute Fibonacci numbers. Its core algorithm is simple. It helps us learn how this sequence is computed.
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