About

COLA2 is a simple solver program for Collatz conjecture (known as 3n+1 problem). About Collatz conjencture, see wikipedia.

In this program, the map for even n|->n/2 is called A, and the map for odd n|->3n+1 is called B.

Requirement

• rustc (>=1.53.0 recommended)

Installation

For Unix-like operating system, simply make it:

make
make install

Usage

1. give numbers via pipeline

echo 153 | cola2
153 36
echo 155555555555555555555555555553 | cola2
155555555555555555555555555553 901

2. give numbers from a file

for i in {1..8}; do
  echo 2^$i-1 | bc
done > num.dat
cola2 < num.dat
1 0
3 7
7 16
15 17
31 106
63 107
127 46
255 47

3. interactive

cola2 <enter>

Tips: Make dot file to visualize convergence process

Following sample script generates a DOT file to visualize Collatz map for numbers less than 257:

{
  echo strict digraph map \{
  for i in {1..256}
  do
    echo $i | cola2 -d
  done
  echo \}
} > collatz_map.dot

Author

Nomura Suzume <suzume315[ATT]g00.g1e.org>