```{index} single: indadd; PDL::Primitive function ``` ```{index} single: PDL::Primitive::indadd; Perl function ``` # indadd `indadd($input, $ind, $sum)` -- broadcasting index-add. Scatter-accumulates values from `$input` into `$sum` at positions given by `$ind`: `sum[ind[n]] += input[n]`. Mirrors upstream `PDL::indadd` (`Primitive.pd` `pp_def 'indadd'`, `Pars => 'input(n); indx ind(n); [io] sum(m)'`). Delegates to the engine's `pdl_run_indadd(input, ind, sum)`. The engine handles type dispatch, broadcasting, bad-value propagation (bad `ind` croaks; bad `input` marks the target element bad), and out-of-range index detection.