Pi Calculator

This is a multi-threaded Rust program that calculates the first n digits of Pi using the Bailey–Borwein–Plouffe (BBP) formula. It uses arbitrary-precision arithmetic (rug) and parallelism (rayon).

Improvements in this branch

• Parallelized BBP summation with rayon for better thread control and load balancing.
• Safer argument validation and error handling (avoids unwraps on runtime errors).
• Optional output-to-file support.
• Added CI workflow to run formatting, clippy, tests and build on push/PR.
• Release profile tuned for better optimized builds (LTO, opt-level=3).

Building

Requires Rust and Cargo. Build with:

cargo build --release

Usage

./target/release/pi <N> [OPTIONS]

Arguments

• <N>: Number of digits after the decimal point to calculate.

Options

• -t, --threads <THREADS>: Number of threads to use (default 4).
• -o, --output <FILE>: Write output to FILE instead of stdout.
• -h, --help: Print help.

Example

Calculate 1000 digits using 8 threads and write to a file:

./target/release/pi 1000 -t 8 -o pi1000.txt

Notes

For very large numbers of digits, using a decimal-friendly algorithm such as Chudnovsky (with binary splitting) will be far faster and more memory-efficient than BBP; consider switching to Chudnovsky for production-grade large computations.