from reading the man page of bc, it seems that bc can accept simple variables, but also arrays as input.
However, if I try to add two arrays, I only get a single element as an output
a=(1 2 3)
b=(10 11 12)
c=`echo "$a + $b" | bc`
Then c only contains 11. If there a way to get bc to operate on all elements in the arrays to produce (11 13 15) as an output? Or do I need to do a loop?
bc can't natively access bash arrays, but you can generate from your two arrays a stream of addition operations, and read their results back into a third array (thus only needing to invoke bc once, rather than running a separate copy of bc per loop entry):
a=(1 2 3)
b=(10 11 12)
readarray -t c < <(for idx in "${!a[@]}"; do
echo "${a[$idx]} + ${b[$idx]}"
done | bc)
declare -p c # print output as an array definition
printf '%s\n' "${c[@]}" # print output one entry per line
See this running at https://ideone.com/YuPhQP, properly emitting as output:
declare -a c=([0]="11" [1]="13" [2]="15")
11
13
15