fixed

commit f60c6583eb0eedc80701c9f22c9921c64a7276bc
parent 711fb0e5286505e5a4688cd35e95d3e49287dc7e
Author: Jared Tobin <jared@jtobin.io>
Date:   Sat,  1 Aug 2026 14:10:27 -0230

lib: document inv of zero

Both inversion chains compute a^(m - 2), so inv zero silently
returns zero; callers that require an error on zero must check for
it themselves.

Diffstat:
M
lib/Numeric/Montgomery/Secp256k1/Curve.hs
 | 
3
+++
M
lib/Numeric/Montgomery/Secp256k1/Scalar.hs
 | 
3
+++

2 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/lib/Numeric/Montgomery/Secp256k1/Curve.hs b/lib/Numeric/Montgomery/Secp256k1/Curve.hs
@@ -762,6 +762,9 @@ inv# a =
 
 -- | Multiplicative inverse in the Montgomery domain.
 --
+--   Note that 'zero' has no multiplicative inverse; 'inv' returns
+--   'zero' when applied to it.
+--
 --   >> inv 2
 --   57896044618658097711785492504343953926634992332820282019728792003954417335832
 --   >> inv 2 * 2
diff --git a/lib/Numeric/Montgomery/Secp256k1/Scalar.hs b/lib/Numeric/Montgomery/Secp256k1/Scalar.hs
@@ -793,6 +793,9 @@ inv# a =
 
 -- | Multiplicative inverse in the Montgomery domain.
 --
+--   Note that 'zero' has no multiplicative inverse; 'inv' returns
+--   'zero' when applied to it.
+--
 --   >> inv 2
 --   57896044618658097711785492504343953926418782139537452191302581570759080747169
 --   >> inv 2 * 2