Yukihiro "Matz" Matsumoto
b7593cde15
Add fast path for multiplying numbers of form 2^n - 1 (all bits set). Uses algebraic identities: - (2^n - 1) * (2^m - 1) = 2^(n+m) - 2^n - 2^m + 1 - (2^n - 1) * y = (y << n) - y These are O(n) operations instead of O(n^1.585) for Karatsuba. Fuzzing test cases using all-ones patterns now complete in 0.01s instead of 13+ seconds. Also raises KARATSUBA_THRESHOLD from 8 to 32 for ~32% speedup on general large number multiplication. Co-authored-by: Claude <noreply@anthropic.com>
mruby-bigint
mruby-bigint is an mrbgem that provides multi-precision integer (BigInt) support for mruby. It allows you to work with integers that are larger than the standard Integer type can handle.
This extension uses fgmp, which is a public domain implementation of a subset of the GNU gmp library by Mark Henderson markh@wimsey.bc.ca. But it's heavily modified to fit with mruby. You can get the original source code from https://github.com/deischi/fgmp.git. You can read the original README for fgmp in README-fgmp.md.
If you want to create your own Multi-precision Integer GEM, see examples/mrbgems/mruby-YOUR-bigint/TODO-HINT.md.
Features
- Basic arithmetic operations:
+,-,*,/,% - Power operation:
** - Modular exponentiation
- Bitwise operations:
&,|,^,<<,>> - Comparison:
<=> - Conversion to and from strings:
to_s,String#to_i(with base) - Square root
- Greatest Common Divisor (GCD) (available if
MRB_USE_RATIONALis defined)
Usage
Here are some simple examples of how to use mruby-bigint:
# Creating BigInts
a = BigInt(12345678901234567890)
b = "98765432109876543210".to_i(10) # Specify base 10 for string conversion
# Arithmetic operations
c = a + b
puts c.to_s # Output: 111111111011111111100
d = a * 2
puts d.to_s # Output: 24691357802469135780
# Comparison
puts a <=> b # Output: -1
fgmp Dependency
mruby-bigint depends on fgmp. For more information about fgmp, please see README-fgmp.md.