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Find the distance between two points
ruby
# the hypotenuse sqrt(x**2+y**2)
distance = Math.hypot(x2-x1,y2-y1)
distance = Math.hypot(x2-x1,y2-y1)
erlang
Distance = distance({point, 34, 78}, {point, 67, -45}),
io:format("~.2f~n", [Distance]).
io:format("~.2f~n", [Distance]).
Distance = distance(point:new(34, 78), point:new(67, -45)),
io:format("~.2f~n", [Distance]).
io:format("~.2f~n", [Distance]).
Zero pad a number
Given the number 42, pad it to 8 characters like 00000042
ruby
42.to_s.rjust(8,"0")
"%08d" % 42
erlang
Formatted = io_lib:format("~8..0B", [42]),
io:format("~8..0B~n", [42]).
Right Space pad a number
Given the number 1024 right pad it to 6 characters
"1024 "
ruby
1024.to_s.ljust(6)
erlang
Formatted = io_lib:format("~-6B", [1024]),
io:format("~-6B~n", [1024]).
Format a decimal number
Format the number 7/8 as a decimal with 2 places: 0.88
ruby
(7.0/8.0*100).round/100.0
(7.0/8.0).round(2)
erlang
Formatted = io_lib:format("~.2f", [7/8]),
io:format("~.2f~n", [7/8]).
Left Space pad a number
Given the number 73 left pad it to 10 characters
" 73"
ruby
73.to_s.rjust(10)
erlang
Formatted = io_lib:format("~10B", [73]),
io:format("~10B~n", [73]).
Generate a random integer in a given range
Produce a random integer between 100 and 200 inclusive
ruby
randomInt = rand(200-100+1)+100;
erlang
RandomInt = gen_rand_integer(100, 200),
Generate a repeatable random number sequence
Initialise a random number generator with a seed and generate five decimal values. Reset the seed and produce the same values.
ruby
srand(12345)
first = (1..5).collect {rand}
srand(12345)
second = (1..5).collect {rand}
puts first == second
first = (1..5).collect {rand}
srand(12345)
second = (1..5).collect {rand}
puts first == second
erlang
setRNG(RNGState),
io:format("~w~n", [lists:map(fun (_) -> gen_rand_integer(100, 200) end, lists:seq(1, 5))]),
setRNG(RNGState),
io:format("~w~n", [lists:map(fun (_) -> gen_rand_integer(100, 200) end, lists:seq(1, 5))]).
io:format("~w~n", [lists:map(fun (_) -> gen_rand_integer(100, 200) end, lists:seq(1, 5))]),
setRNG(RNGState),
io:format("~w~n", [lists:map(fun (_) -> gen_rand_integer(100, 200) end, lists:seq(1, 5))]).
