Generates a rainbow in bash (truecolor)

rainbow.sh

center=128
width=127
freq=0.06
rainbow() {
    R=$(bc -l <<< "scale=2;s($freq*$1+2)*$width+$center")
    G=$(bc -l <<< "scale=2;s($freq*$1+0)*$width+$center")
    B=$(bc -l <<< "scale=2;s($freq*$1+4)*$width+$center")
    echo "\x1b[38;2;${R%.*};${G%.*};${B%.*}m"
}

# Example usage:
# colorCode=$(rainbow 1)

# Make big block of text rainbow
# newString=""
# IFS=$'\n'
# for i in $string; do
#    for ((n=0; n<=${#i}-1; n++)); do
#        newString="$newString$(rainbow $n)${i:$n:1}";
#    done
#    newString="$newString\n"
# done