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