26 lines
1.1 KiB
Markdown
26 lines
1.1 KiB
Markdown
# Comparisons & ranges {#comparisons}
|
|
|
|
A distributed comparison function returns a payload when a predicate holds
|
|
on the secret point. Shares are additive: `reconstruct` adds them.
|
|
|
|
| Call | When it is hot |
|
|
| --- | --- |
|
|
| `dpf::lt` / `leq` / `gt` / `geq` | The public query is on that side of the secret point |
|
|
| `dpf::eq` | The public query equals the secret point |
|
|
| `dpf::ic` | The secret point lies in a public interval |
|
|
| `dpf::idcf` / `cmp_prefix<L>` | A correction at every depth, or only the first `L` bits |
|
|
| `dpf::block_width<B>` | Ring words only at checkpoints `B` levels apart |
|
|
|
|
```cpp
|
|
auto [k0, k1] = dpf::make_dpf(std::uint8_t{40}, dpf::gt(std::uint64_t{1}));
|
|
auto opened = dpf::reconstruct(
|
|
dpf::eval_point(dpf::cmp, k0, std::uint8_t{50}),
|
|
dpf::eval_point(dpf::cmp, k1, std::uint8_t{50}));
|
|
// opened == 1
|
|
```
|
|
|
|
A wildcard comparison payload is filled later with `assign_cmp`.
|
|
Eval before that throws.
|
|
|
|
**Go deeper:** [dcf.hpp](@ref dpf/dcf.hpp), [interval.hpp](@ref dpf/interval.hpp),
|
|
[blocked_dcf.hpp](@ref dpf/blocked_dcf.hpp), [F_DCF](@ref dcf.hpp).
|