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README.md

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+# BigIntLua
+
+Pure Lua library for working with big integers
+
+
+# Usage
+
+```lua
+BigInt = require 'bigint'
+
+-- constructor accepts a number
+a1 = BigInt(562949953421312)
+
+-- or a string
+a2 = BigInt'562949953421312'
+
+-- or a string with thousands separator of ',' or whitespace
+a3 = BigInt'562,949,953,421,312'
+a4 = BigInt'562 949 953 421 312'
+a1 == a2            --> true
+a1 == a3            --> true
+a3 == a4            --> true
+
+
+-- you can compare them
+a = BigInt'8,796,093,022,208'
+b = BigInt'562,949,953,421,312'
+c = BigInt'39,614,081,257,132,168,796,771,975,168'
+a == a1             --> true
+a <= a1             --> true
+a == b              --> false
+a <= b              --> true
+c > a               --> true
+
+-- NOTE: equality test works only with two BigInts
+a = BigInt'562949953421312'
+a == 562949953421312    --> false
+
+-- NOTE: other comparisons between Lua Numbers and BigInts are ok
+a = BigInt'56294995342'
+a <= 56294995342    --> true
+a > 12323           --> true
+a >= 56294995342    --> true
+32423412312 < a     --> true
+32423412312 > a     --> false
+
+-- four arithmetic operations
+a = BigInt'1,099,511,627,776'           -- 2 ^ 40
+b = BigInt'1,125,899,906,842,624'       -- 2 ^ 50
+a + b               --> 1126999418470400
+a - b               --> -1124800395214848
+a * b               --> 1237940039285380274899124224
+a / b               --> 0
+b / a               --> 1024
+
+-- negation
+a = BigInt'562949953421312'
+b = -a              --> -562949953421312
+a + b               --> 0
+
+-- divmod
+a = BigInt'1,099,511,627,776'           -- 2 ^ 40
+b = BigInt'1,125,899,906,842,625'       -- 2 ^ 50 + 1
+b:divmod(b, a)      --> 1024, 1
+
+-- power
+a = BigInt(2)
+a ^ 95              --> 39614081257132168796771975168
+```
+
+# TODO
+- Optional thousands separator in `tostring()` function.
+- GCD and LCD
+- Base conversion
+- Prime check
+- Prime factorization
+
+
+
+# See also
+- [https://github.com/user-none/lua-nums]()
+- [https://github.com/empyreuma/bigint.lua]()
+- [https://github.com/thenumbernine/lua-bignumber]()
+- [https://github.com/A-Benlolo/BigInteger.lua]()
+