Ein Anderssono
54d2fecee0
- Added implementations for: bash, brainfuck, c, cpp, crystal, csharp, d, dart, elixir, erlang, fortran, go, haskell, java, javascript, julia, kotlin, objective-c, scala, typescript, lua, nim, odin, perl, php, python, r, ruby, rust, swift, zig, assembly, vimscript, wolfram - All implementations use Machin's formula: π/4 = 4*arctan(1/5) - arctan(1/239) - Build system with ./build.sh, test system with ./test.sh - Performance testing with ./run_all.sh - Comprehensive README.md explaining performance differences - Test framework verifies correctness against known π values
64 lines
2.0 KiB
Erlang
64 lines
2.0 KiB
Erlang
-module(print_hej).
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-export([main/1, pow/2]).
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main(Args) ->
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Decimals = case Args of
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[] -> 100;
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[X | _] ->
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case string:to_integer(X) of
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{D, _} when D > 0 -> D;
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_ -> 100
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end
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end,
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Pi = calculate_pi(Decimals),
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PiStr = format_pi(Pi, Decimals),
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io:format("~s~n", [PiStr]),
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erlang:halt(0).
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% Calculate arctan(1/x) using Taylor series
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% arctan(1/x) = 1/x - 1/(3*x^3) + 1/(5*x^5) - ...
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arctan(X, Decimals) ->
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Scale = pow(10, Decimals + 10),
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XSquared = X * X,
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Term = Scale div X, % First term: scale / x
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arctan_iter(XSquared, Term, 0, 0, Decimals).
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arctan_iter(_XSquared, Term, N, Result, Decimals) when Term == 0; N > Decimals * 3 ->
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Result;
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arctan_iter(XSquared, Term, N, Result, Decimals) ->
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Divisor = 2 * N + 1,
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Contrib = Term div Divisor,
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NewResult = case N rem 2 of
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0 -> Result + Contrib;
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1 -> Result - Contrib
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end,
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NewTerm = Term div XSquared, % Divide by x² each iteration
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arctan_iter(XSquared, NewTerm, N + 1, NewResult, Decimals).
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% Calculate pi using Machin's formula
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% pi/4 = 4*arctan(1/5) - arctan(1/239)
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calculate_pi(Decimals) ->
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Atan1_5 = arctan(5, Decimals),
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Atan1_239 = arctan(239, Decimals),
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16 * Atan1_5 - 4 * Atan1_239.
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% Format pi with decimal point
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format_pi(Pi, Decimals) ->
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PiStr = integer_to_list(Pi),
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% Pad with leading zeros if needed
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PiStr2 = case length(PiStr) < Decimals + 10 of
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true -> string:left(PiStr, Decimals + 10, $0);
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false -> PiStr
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end,
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"3." ++ string:substr(PiStr2, 2, Decimals).
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% Power function for integers
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pow(Base, Exp) when Exp >= 0 ->
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pow_iter(Base, Exp, 1).
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pow_iter(_Base, 0, Acc) -> Acc;
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pow_iter(Base, Exp, Acc) when Exp rem 2 == 0 ->
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pow_iter(Base * Base, Exp div 2, Acc);
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pow_iter(Base, Exp, Acc) ->
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pow_iter(Base, Exp - 1, Acc * Base). |