From 7825d9e60f86a26c3c4da85de6511a38ef6a7af8 Mon Sep 17 00:00:00 2001
From: Matt Borland <matt@mattborland.com>
Date: Tue, 10 Mar 2026 11:14:41 -0400
Subject: [PATCH] Add legacy functions build option to Math section

Add new `BOOST_MATH_BUILD_WITH_LEGACY_FUNCTIONS` description.

Related PR: https://github.com/boostorg/math/pull/1376
Derived from: https://github.com/microsoft/vcpkg/pull/38728
---
 README.md | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/README.md b/README.md
index 5b86569..8f6ce3f 100644
--- a/README.md
+++ b/README.md
@@ -293,6 +293,14 @@ are given below.
   When ON, enables the Windows API backend. Defaults to ON under Windows, OFF
   otherwise.
 
+### Math
+
+* `BOOST_MATH_BUILD_WITH_LEGACY_FUNCTIONS`
+
+  When ON, builds the C99/TR1 targets as: `boost_math_c99f` `boost_math_c99`, `boost_math_c99l` (if your platform has long double support),
+   `boost_math_tr1f`, `boost_math_tr1`, and `boost_math_tr1l` (if your platform has long double support).
+  With CMake Version >= 3.13 these 4-6 targets can be linked with the single target `boost_math_legacy_targets`. Defaults to OFF.
+
 ### Stacktrace
 
 * `BOOST_STACKTRACE_ENABLE_NOOP`