Function: fib

Add next number in fibonacci series to end of array

USAGE: fib arrayname

fib()
{    
  local arrayname=${1:?} array
  

Copy the array, $arrayname, to local array

  eval "array=( \"\${$arrayname[@]}\" )"
  

If there are no elements in the array, enter the first two

  if [ ${#array[@]} -eq 0 ]
  then
    array=( 0 1 )
  elif [ ${#array[@]} -eq 1 ]
  

If there is one element in the array, enter a second

  then
    array[1]=$(( array[0] + 1 ))
  else
    array+=( $(( array[-1] + array[-2] )) )
  fi
  

Copy array back to $arrayname

  eval "$arrayname=( \"\${array[@]}\" )"
}