[Help-bash] howto pass bash array to bc

[lxnf98mm]

I know this is not strickly bash but ...
If I have a bash array, a=("1" "2" "3"), and I want to pass this array to 
bc for some computations, how do I/can I do this?

echo "\
define z(a[]) {
  j = 1;
  print a[j];
}
z(address@hidden)" | bc -l

Richard