From fbf648c9a4c751fc3041c14983ff55c3254a5c56 Mon Sep 17 00:00:00 2001
From: Giovanni Mascellani <gio@debian.org>
Date: Wed, 8 Apr 2020 09:00:33 +0200
Subject: [PATCH] Implement floor() and ceil() for rational types.

---
 .../boost/multiprecision/rational_adaptor.hpp | 20 +++++++++++++++++++
 test/test_arithmetic.hpp                      | 11 ++++++++++
 2 files changed, 31 insertions(+)

diff --git a/include/boost/multiprecision/rational_adaptor.hpp b/include/boost/multiprecision/rational_adaptor.hpp
index 2d839bb1c..dc2e29124 100644
--- a/include/boost/multiprecision/rational_adaptor.hpp
+++ b/include/boost/multiprecision/rational_adaptor.hpp
@@ -318,6 +318,26 @@ inline number<IntBackend, ET> denominator(const number<rational_adaptor<IntBacke
 {
    return val.backend().data().denominator();
 }
+template <class IntBackend, expression_template_option ET>
+inline number<IntBackend, ET> floor(const number<rational_adaptor<IntBackend>, ET>& val)
+{
+    // Here we use the assumption that denominator is always positive
+    // and numerator has the sign
+    if (val >= 0)
+        return numerator(val) / denominator(val);
+    else
+        return (numerator(val) + 1) / denominator(val) - 1;
+}
+template <class IntBackend, expression_template_option ET>
+inline number<IntBackend, ET> ceil(const number<rational_adaptor<IntBackend>, ET>& val)
+{
+    // Here we use the assumption that denominator is always positive
+    // and numerator has the sign
+    if (val >= 0)
+        return (numerator(val) - 1) / denominator(val) + 1;
+    else
+        return numerator(val) / denominator(val);
+}
 
 #ifdef BOOST_NO_SFINAE_EXPR
 
diff --git a/test/test_arithmetic.hpp b/test/test_arithmetic.hpp
index 301a6b5b1..c1e52fc43 100644
--- a/test/test_arithmetic.hpp
+++ b/test/test_arithmetic.hpp
@@ -293,6 +293,17 @@ void test_rational(const boost::mpl::false_&)
 #endif
    b = Real("2/3");
    BOOST_CHECK_EQUAL(a, b);
+
+   const static int floor_ceil_data[][4] = {{-11, 10, -2, -1}, {-10, 10, -1, -1}, {-9, 10, -1, 0},
+                                            {-1, 10, -1, 0}, {0, 10, 0, 0}, {1, 10, 0, 1},
+                                            {9, 10, 0, 1}, {10, 10, 1, 1}, {11, 10, 1, 2}};
+   for (unsigned int i = 0; i < sizeof(floor_ceil_data) / sizeof(floor_ceil_data[0]); i++) {
+       Real c(floor_ceil_data[i][0]);
+       c /= floor_ceil_data[i][1];
+       BOOST_CHECK_EQUAL(floor(c), floor_ceil_data[i][2]);
+       BOOST_CHECK_EQUAL(ceil(c), floor_ceil_data[i][3]);
+   }
+
    //
    // Check IO code:
    //