Repeating sequence in a range in bash and terraform

repeating-sequence-in-a-range.bash

#!/usr/bin/env bash
set -eou pipefail

cat <<'EOF'
This script demonstrates how repeating sequence in a range works

Formula:

  (((N + 1) % n) ^ (((N + 1) / n) % 2)) * (N + 1)

Bash:

  $(((((N + 1) % n) ** (((N + 1) / n) % 2)) * (N + 1)))

Terraform:

  pow((($N + 1) % n), (floor(($N + 1) / n) % 2)) * ($N + 1)

Where N is the current number and n max value in the range with zero as the minimum value.
N can be initialized with -1 to start the sequence from 0.

Special operators:
  ^ - power operator
  ** - power operator (for bash)
  % - modulo operator
EOF

n=${1:-11}
N=${1:--1}
_N=$N

echo -e "\nSequence using bash: n=$n, N=$N"
for _ in $(seq 0 $((n + 2))); do
  new_N=$(((((N + 1) % n) ** (((N + 1) / n) % 2)) * (N + 1)))
  if [ $new_N -eq 0 ]; then
    echo "N=$new_N # Resetting the sequence"
  else
    echo "N=$new_N"
  fi
  N=$new_N
done

N=$_N
echo -e "\nSequence using terraform: n=$n, N=$N"
for _ in $(seq 0 $((n + 2))); do
  new_N="$(echo "pow((($N + 1) % $n), (floor(($N + 1) / $n) % 2)) * ($N + 1)" | terraform console)"
  if [ "$new_N" -eq 0 ]; then
    echo "N=$new_N # Resetting the sequence"
  else
    echo "N=$new_N"
  fi
  N=$new_N
done

stdout

This script demonstrates how repeating sequence in a range works

Formula:

  (((N + 1) % n) ^ (((N + 1) / n) % 2)) * (N + 1)

Bash:

  $(((((N + 1) % n) ** (((N + 1) / n) % 2)) * (N + 1)))

Terraform:

  pow((($N + 1) % n), (floor(($N + 1) / n) % 2)) * ($N + 1)

Where N is the current number and n max value in the range with zero as the minimum value.
N can be initialized with -1 to start the sequence from 0.

Special operators:
  ^ - power operator
  ** - power operator (for bash)
  % - modulo operator

Sequence using bash: n=11, N=-1
N=0 # Resetting the sequence
N=1
N=2
N=3
N=4
N=5
N=6
N=7
N=8
N=9
N=10
N=0 # Resetting the sequence
N=1
N=2

Sequence using terraform: n=11, N=-1
N=0 # Resetting the sequence
N=1
N=2
N=3
N=4
N=5
N=6
N=7
N=8
N=9
N=10
N=0 # Resetting the sequence
N=1
N=2