Functions and Fractals - Recursive Trees - Bash!

#!/bin/nash
showStepY() {
    local WIDTH="$1"; shift
    local LEVEL="$1"; shift
    local CHAR="$1"; shift
    local MAXLEVEL=0
    local MAXSIZE=1
    local SIZE=1
    local REPEAT=1
    while [ $(($MAXSIZE*2)) -lt "$WIDTH" ]; do
        MAXSIZE=$(($MAXSIZE*2))
        MAXLEVEL=$(($MAXLEVEL+1))
        if [ "$MAXLEVEL" -le "$LEVEL" ]; then
            SIZE=$(($SIZE*2))
        else
            REPEAT=$(($REPEAT*2))
        fi
    done
    local INDENT=$(( ($WIDTH-$MAXSIZE)/2 ))
    local LINES=$(($SIZE/2))
    {
        if [ "$LINES" -gt 0 ]; then
            for i in `seq 0 $(($LINES-1))`; do
                printf '%*s' $INDENT ''
                for j in `seq 1 $(($REPEAT/2))`; do
                    printf '%*s%*s%*s' $(($SIZE/2+$i)) "$CHAR" $(($SIZE-$i*2)) "$CHAR" $(($SIZE/2+$i)) ''
                done
                printf '%*s\n' $(($INDENT)) ''
            done
        fi
        for i in `seq $(($SIZE-$LINES)) -1 1`; do
            printf '%*s' $INDENT ''
            for j in `seq 1 $(($REPEAT/2))`; do
                printf '%*s%*s' $SIZE "$CHAR" $SIZE ''
            done
            printf '%*s\n' $INDENT ''
        done
    } | tr ' ' _
    return
}

showYTree() {
    local WIDTH="$1"; shift
    local MAXLEVEL="$1"; shift
    local ITER="$1"; shift
    for i in `seq 0 $MAXLEVEL`; do
        local CHAR=''
        [ $(($ITER+$i)) -le $MAXLEVEL ] || CHAR=1
        showStepY "$WIDTH" "$i" "$CHAR"
    done
}

read ITER
showYTree 100 5 "$ITER"