From a39c9a3e09f30796231343f5015c580f72ba4c67 Mon Sep 17 00:00:00 2001
From: Sam Yates <halfflat@gmail.com>
Date: Thu, 27 Oct 2016 22:13:39 +0200
Subject: [PATCH] Unit tests for math.hpp
* Tests for `math::pi`, `math::lerp`, `math::area_frustrum`
and `math::volume_frustrum`
* Fix `math:pi<long double>()`.
---
src/math.hpp | 2 +-
tests/unit/test_math.cpp | 72 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 73 insertions(+), 1 deletion(-)
diff --git a/src/math.hpp b/src/math.hpp
index bf964ba3..36767bcb 100644
--- a/src/math.hpp
+++ b/src/math.hpp
@@ -11,7 +11,7 @@ namespace math {
template <typename T>
T constexpr pi()
{
- return T(3.1415926535897932384626433832795);
+ return T(3.1415926535897932384626433832795l);
}
template <typename T = float>
diff --git a/tests/unit/test_math.cpp b/tests/unit/test_math.cpp
index b32bd194..5dff6c81 100644
--- a/tests/unit/test_math.cpp
+++ b/tests/unit/test_math.cpp
@@ -6,6 +6,78 @@
using namespace nest::mc::math;
+TEST(math, pi) {
+ // check regression against long double literal in implementation
+ auto pi_ld = pi<long double>();
+ auto pi_d = pi<double>();
+
+ if (std::numeric_limits<long double>::digits>std::numeric_limits<double>::digits) {
+ EXPECT_NE(0.0, pi_ld-pi_d);
+ }
+ else {
+ EXPECT_EQ(0.0, pi_ld-pi_d);
+ }
+
+ // library quality of implementation dependent, but expect cos(pi) to be within
+ // 1 epsilon of -1.
+
+ auto eps_d = std::numeric_limits<double>::epsilon();
+ auto cos_pi_d = std::cos(pi_d);
+ EXPECT_LE(-1.0-eps_d, cos_pi_d);
+ EXPECT_GE(-1.0+eps_d, cos_pi_d);
+
+ auto eps_ld = std::numeric_limits<long double>::epsilon();
+ auto cos_pi_ld = std::cos(pi_ld);
+ EXPECT_LE(-1.0-eps_ld, cos_pi_ld);
+ EXPECT_GE(-1.0+eps_ld, cos_pi_ld);
+}
+
+TEST(math, lerp) {
+ // expect exact computation when u is zero or one
+ double a = 1.0/3;
+ double b = 11.0/7;
+
+ EXPECT_EQ(a, lerp(a, b, 0.));
+ EXPECT_EQ(b, lerp(a, b, 1.));
+
+ // expect exact computation here as well
+ EXPECT_EQ(2.75, lerp(2.0, 3.0, 0.75));
+
+ // and otherwise to be close
+ EXPECT_DOUBLE_EQ(100.101, lerp(100.1, 200.1, 0.00001));
+ EXPECT_DOUBLE_EQ(200.099, lerp(100.1, 200.1, 0.99999));
+
+ // should be able to lerp with differing types for end points and u
+ EXPECT_EQ(0.25f, lerp(0.f, 1.f, 0.25));
+}
+
+TEST(math, frustrum) {
+ // cross check against cone calculation
+ auto cone_area = [](double l, double r) {
+ return std::hypot(l,r)*r*pi<double>();
+ };
+
+ auto cone_volume = [](double l, double r) {
+ return pi<double>()*square(r)*l/3.0;
+ };
+
+ EXPECT_DOUBLE_EQ(cone_area(5.0, 1.3), area_frustrum(5.0, 0.0, 1.3));
+ EXPECT_DOUBLE_EQ(cone_volume(5.0, 1.3), volume_frustrum(5.0, 0.0, 1.3));
+
+ double r1 = 7.0;
+ double r2 = 9.0;
+ double l = 11.0;
+
+ double s = l*r2/(r2-r1);
+ double ca = cone_area(s, r2)-cone_area(s-l, r1);
+ double cv = cone_volume(s, r2)-cone_volume(s-l, r1);
+
+ EXPECT_DOUBLE_EQ(ca, area_frustrum(l, r1, r2));
+ EXPECT_DOUBLE_EQ(ca, area_frustrum(l, r2, r1));
+ EXPECT_DOUBLE_EQ(cv, volume_frustrum(l, r1, r2));
+ EXPECT_DOUBLE_EQ(cv, volume_frustrum(l, r2, r1));
+}
+
TEST(math, infinity) {
// check values for float, double, long double
auto finf = infinity<float>();
--
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