#!/bin/sh

#-----[ usage ]---------------------------------------------
function usage ()
{
    echo "Usage     : ${0} min max [step [iter]]";
    echo "Arguments : ";
    echo " * min  : value minimal";
    echo " * max  : value maximal";
    echo " * step : step between two value. If no present, step = \"+1\"";
    echo " * iter : choose the Nième value";
    exit;
}

#-----[ range ]---------------------------------------------
function range ()
{
    declare a=${1};
    declare b=${2};
    declare step=${3};

    while test ${a} -lt ${b}; do
        echo ${a};
        a=$((${a} ${step}));
    done

    if test ${a} -eq ${b}; then
	echo ${a};
    fi;
}

#-----[ range_max ]-----------------------------------------
function range_max ()
{
    declare a=${1};
    declare b=${2};
    declare step=${3};
    declare iter=${4};

    while test ${a} -lt ${b} -a ${iter} -gt 1; do
	a=$((${a} ${step}));
	iter=$((${iter}-1));
    done;

    if test ${a} -eq ${b}; then
	echo ${a};
    fi;

    if test ${iter} -eq 1; then
	echo ${a};
    fi;
}

#-----[ main ]----------------------------------------------
function main ()
{
    # create operande
    case ${#} in
	2) range ${*} "+1";;
	3) range ${*}     ;;
	4) range_max ${*} ;;
	*) usage ${*}
    esac
}

#-----[ Corps ]---------------------------------------------
main ${*}