integer square root 'calculation' for ints between 1..255

int_sqrt.rb

require 'benchmark'

def sqrt_calc
  sqrt_hash = integer_sqrt_hash # instantiating hash table
  
  n = 30000000 # number of test cycles to benchmark
  Benchmark.bm do |x|
    x.report do
      n.times do 
        rgb_val = rand(1..255); 
        int_sqrt = sqrt_hash[rgb_val]; 
        # puts "#{rgb_val}, #{int_sqrt}" 
      end
    end
  end
end

# Benchmark Results
#     user     system      total        real
# 3.360000   0.000000   3.360000 (  3.356045)

def integer_sqrt_hash
  {
    1 =>  1.00,
    2 =>  1.41,
    3 =>  1.73,
    4 =>  2.00,
    5 =>  2.24,
    6 =>  2.45,
    7 =>  2.65,
    8 =>  2.83,
    9 =>  3.00,
    10  =>  3.16,
    11  =>  3.32,
    12  =>  3.46,
    13  =>  3.61,
    14  =>  3.74,
    15  =>  3.87,
    16  =>  4.00,
    17  =>  4.12,
    18  =>  4.24,
    19  =>  4.36,
    20  =>  4.47,
    21  =>  4.58,
    22  =>  4.69,
    23  =>  4.80,
    24  =>  4.90,
    25  =>  5.00,
    26  =>  5.10,
    27  =>  5.20,
    28  =>  5.29,
    29  =>  5.39,
    30  =>  5.48,
    31  =>  5.57,
    32  =>  5.66,
    33  =>  5.74,
    34  =>  5.83,
    35  =>  5.92,
    36  =>  6.00,
    37  =>  6.08,
    38  =>  6.16,
    39  =>  6.24,
    40  =>  6.32,
    41  =>  6.40,
    42  =>  6.48,
    43  =>  6.56,
    44  =>  6.63,
    45  =>  6.71,
    46  =>  6.78,
    47  =>  6.86,
    48  =>  6.93,
    49  =>  7.00,
    50  =>  7.07,
    51  =>  7.14,
    52  =>  7.21,
    53  =>  7.28,
    54  =>  7.35,
    55  =>  7.42,
    56  =>  7.48,
    57  =>  7.55,
    58  =>  7.62,
    59  =>  7.68,
    60  =>  7.75,
    61  =>  7.81,
    62  =>  7.87,
    63  =>  7.94,
    64  =>  8.00,
    65  =>  8.06,
    66  =>  8.12,
    67  =>  8.19,
    68  =>  8.25,
    69  =>  8.31,
    70  =>  8.37,
    71  =>  8.43,
    72  =>  8.49,
    73  =>  8.54,
    74  =>  8.60,
    75  =>  8.66,
    76  =>  8.72,
    77  =>  8.77,
    78  =>  8.83,
    79  =>  8.89,
    80  =>  8.94,
    81  =>  9.00,
    82  =>  9.06,
    83  =>  9.11,
    84  =>  9.17,
    85  =>  9.22,
    86  =>  9.27,
    87  =>  9.33,
    88  =>  9.38,
    89  =>  9.43,
    90  =>  9.49,
    91  =>  9.54,
    92  =>  9.59,
    93  =>  9.64,
    94  =>  9.70,
    95  =>  9.75,
    96  =>  9.80,
    97  =>  9.85,
    98  =>  9.90,
    99  =>  9.95,
    100 =>  10.00,
    101 =>  10.05,
    102 =>  10.10,
    103 =>  10.15,
    104 =>  10.20,
    105 =>  10.25,
    106 =>  10.30,
    107 =>  10.34,
    108 =>  10.39,
    109 =>  10.44,
    110 =>  10.49,
    111 =>  10.54,
    112 =>  10.58,
    113 =>  10.63,
    114 =>  10.68,
    115 =>  10.72,
    116 =>  10.77,
    117 =>  10.82,
    118 =>  10.86,
    119 =>  10.91,
    120 =>  10.95,
    121 =>  11.00,
    122 =>  11.05,
    123 =>  11.09,
    124 =>  11.14,
    125 =>  11.18,
    126 =>  11.22,
    127 =>  11.27,
    128 =>  11.31,
    129 =>  11.36,
    130 =>  11.40,
    131 =>  11.45,
    132 =>  11.49,
    133 =>  11.53,
    134 =>  11.58,
    135 =>  11.62,
    136 =>  11.66,
    137 =>  11.70,
    138 =>  11.75,
    139 =>  11.79,
    140 =>  11.83,
    141 =>  11.87,
    142 =>  11.92,
    143 =>  11.96,
    144 =>  12.00,
    145 =>  12.04,
    146 =>  12.08,
    147 =>  12.12,
    148 =>  12.17,
    149 =>  12.21,
    150 =>  12.25,
    151 =>  12.29,
    152 =>  12.33,
    153 =>  12.37,
    154 =>  12.41,
    155 =>  12.45,
    156 =>  12.49,
    157 =>  12.53,
    158 =>  12.57,
    159 =>  12.61,
    160 =>  12.65,
    161 =>  12.69,
    162 =>  12.73,
    163 =>  12.77,
    164 =>  12.81,
    165 =>  12.85,
    166 =>  12.88,
    167 =>  12.92,
    168 =>  12.96,
    169 =>  13.00,
    170 =>  13.04,
    171 =>  13.08,
    172 =>  13.11,
    173 =>  13.15,
    174 =>  13.19,
    175 =>  13.23,
    176 =>  13.27,
    177 =>  13.30,
    178 =>  13.34,
    179 =>  13.38,
    180 =>  13.42,
    181 =>  13.45,
    182 =>  13.49,
    183 =>  13.53,
    184 =>  13.56,
    185 =>  13.60,
    186 =>  13.64,
    187 =>  13.67,
    188 =>  13.71,
    189 =>  13.75,
    190 =>  13.78,
    191 =>  13.82,
    192 =>  13.86,
    193 =>  13.89,
    194 =>  13.93,
    195 =>  13.96,
    196 =>  14.00,
    197 =>  14.04,
    198 =>  14.07,
    199 =>  14.11,
    200 =>  14.14,
    201 =>  14.18,
    202 =>  14.21,
    203 =>  14.25,
    204 =>  14.28,
    205 =>  14.32,
    206 =>  14.35,
    207 =>  14.39,
    208 =>  14.42,
    209 =>  14.46,
    210 =>  14.49,
    211 =>  14.53,
    212 =>  14.56,
    213 =>  14.59,
    214 =>  14.63,
    215 =>  14.66,
    216 =>  14.70,
    217 =>  14.73,
    218 =>  14.76,
    219 =>  14.80,
    220 =>  14.83,
    221 =>  14.87,
    222 =>  14.90,
    223 =>  14.93,
    224 =>  14.97,
    225 =>  15.00,
    226 =>  15.03,
    227 =>  15.07,
    228 =>  15.10,
    229 =>  15.13,
    230 =>  15.17,
    231 =>  15.20,
    232 =>  15.23,
    233 =>  15.26,
    234 =>  15.30,
    235 =>  15.33,
    236 =>  15.36,
    237 =>  15.39,
    238 =>  15.43,
    239 =>  15.46,
    240 =>  15.49,
    241 =>  15.52,
    242 =>  15.56,
    243 =>  15.59,
    244 =>  15.62,
    245 =>  15.65,
    246 =>  15.68,
    247 =>  15.72,
    248 =>  15.75,
    249 =>  15.78,
    250 =>  15.81,
    251 =>  15.84,
    252 =>  15.87,
    253 =>  15.91,
    254 =>  15.94,
    255 =>  15.97 
  }
end

sqrt_calc