So the deadline has passed. Has anybody got any code they wish to share?
I'll start off by just posting a partial solution - the piece of code
people I was training thought was so elegant, but I think is a bit
ugly. Please bear in mind I wrote this "live" in a classroom, so it's
far from perfect:
-----
# Seed our first two values
a, b = 0, 1
# Calculte the next number in sequence given two values,
# and return two values
def next_fib(x, y)
return y, x + y
end
infinite = false
iterations = 10
count = 2
# Just loops over iterations or to infinity
while count <= iterations or infinite
puts a if count == 2 # Print out a only on first iteration
puts b # Print out b always
a, b = next_fib(a, b) # Increment the values
count += 1
end
# I want a predicate method for numbers to test if the number is
# Fibonnaci so extend the Fixnum class and add my own method
class Fixnum
# A brute force method, fine for small integers
# but Wikipedia has a solution more suitable for
# very large numbers
def is_fibonnaci?
a, b = 0, 1
puts "testing #{self.to_i}"
while b < self # If smaller, keep going
a, b = next_fib(a, b) # Note, needs above method
end
return true if b == self # If equal, must be Fibonacci
return false # Otherwise we've gone past it, so return false
end
end
puts "1 returns #{1.is_fibonnaci?}"
puts "6 returns #{1.is_fibonnaci?}"
-----
The bits that raised eyebrows in my class:
- Returning two values, which is perfectly legal in Ruby. I'd spent
the morning talking about different ways to return things in Ruby and
what would happen if I'd done "a = next_fib(a, b)" or ",b =
next_fib(a, b)" so added this in to make a point more than anything
- "while count <= iterations or infinite" does not test if count is
less than infinite. While sees two tests here: count <= iterations OR
infinite. If infinite is true, it will therefore never end
- Extending Fixnum to add my own methods.
- The fact I wait until I've gone past my value and then test for
equality (in which case it's Fib), otherwise just return false some
people see as "sloppy" or even "cheating".
Comments? Thoughts? Bring your code out...
--
Paul Robinson
http://vagueware.com :: [EMAIL PROTECTED] :: +44 (0) 7740 465746
Vagueware Limited is registered in England/Wales, number 05700421
Registered Office: 3 Tivoli Place, Ilkley, W. Yorkshire, LS29 8SU
Correspondence: 55 Velvet Court, Granby Row, Manchester, M1 7AB
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