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# The Computer Language Benchmarks Game
# http://shootout.alioth.debian.org/
#
# contributed by Karl von Laudermann
# modified by Jeremy Echols
# modified by Detlef Reichl
#size = ARGV[0].to_i
size = 256
puts "P4\n#{size} #{size}"
ITER = 50 # Iterations
LIMIT_SQUARED = 4.0 # Presquared limit
byte_acc = 0
bit_num = 0
count_size = size - 1 # Precomputed size for easy for..in looping
# For..in loops are faster than .upto, .downto, .times, etc.
# That's not true, but left it here
for y in 0..count_size
for x in 0..count_size
zr = 0.0
zi = 0.0
cr = (2.0*x.to_f/size.to_f)-1.5
ci = (2.0*y.to_f/size.to_f)-1.0
escape = false
zrzr = zr*zr
zizi = zi*zi
ITER.times do
tr = zrzr - zizi + cr
ti = 2.0*zr*zi + ci
zr = tr
zi = ti
# preserve recalculation
zrzr = zr*zr
zizi = zi*zi
if zrzr+zizi > LIMIT_SQUARED
escape = true
break
end
# nil
end
byte_acc = (byte_acc << 1) | (escape ? 0b0 : 0b1)
bit_num += 1
# Code is very similar for these cases, but using separate blocks
# ensures we skip the shifting when it's unnecessary, which is most cases.
if (bit_num == 8)
printf "%c", byte_acc # .chr
byte_acc = 0
bit_num = 0
elsif (x == count_size)
byte_acc <<= (8 - bit_num)
printf "%c", byte_acc # .chr
byte_acc = 0
bit_num = 0
else
0
end
# nil
end
end