Calculates Fibonacci numbers with arbitrary precision. Fast doubling is used as Fibonacci alforithm which is explanied by Chun-Min Chang, and Karatsuba algoritm for multiplication inspired by the Vladimir Petrigo implementation for big numbers.

Arbitrary precision is achieved through a custom bigint class (only for positive numbers) with multiplication, addition and subtraction operators overloaded. Also, the std::string conversion operator is overloaded.

Use the Makefile file to build the binary. There are some targets available:

• release: The default target generates de optimized binary at bin/bigfib.
• debug: Generates the binary for debugging with gdb.
• clean: Removes all the compilation files.

Feel free to update the CXX, CXXFLAGS, LIBS and LDFLAGS variables if you need.

Usage: bin/bigfib [OPTIONS]... N...
Calculate the Fibonacci number of the given N terms.

  -q, --quiet          don't print the Fibonacci number
  -s, --simple         don't print summary.
  -h, --help           display this help and exit
  -v, --version        output version information and exit

Some outputs using the quiet options to avoid the Fibonacci number printing. All tests have been executed on a AMD Ryzen™ 7 5700U:

Term: 512
Chunks: 12
Digits: 107
Calculating time:       0.013195 ms
Casting time:           0.015670 ms
Total time:             0.028865 ms

Term: 4784969
Chunks: 111112
Digits: 1000000
Calculating time:     220.479498 ms
Casting time:           3.840622 ms
Total time:           224.320120 ms

Term: 100000000
Chunks: 2322085
Digits: 20898764
Calculating time:   52460.604902 ms
Casting time:          76.934597 ms
Total time:         52537.539499 ms

Licensed under the MIT license.

Share and enjoy!