Add bhaskara sine approximation

CMakeLists.txt

@@ -78,6 +78,7 @@ if(NOT CMAKE_CROSSCOMPILING)
             "lib/grit/math/power_test.cpp"
             "lib/grit/math/normalizable_range_test.cpp"
             "lib/grit/math/static_lookup_table_test.cpp"
+            "lib/grit/math/trigonometry_test.cpp"
             "lib/grit/unit/decibel_test.cpp"
     )
 

lib/CMakeLists.txt

@@ -78,6 +78,7 @@ target_sources(gritwave-grit INTERFACE
         "grit/math/sign.hpp"
         "grit/math/static_lookup_table.hpp"
         "grit/math/static_lookup_table_transform.hpp"
+        "grit/math/trigonometry.hpp"
 
         "grit/unit.hpp"
         "grit/unit/decibel.hpp"

lib/grit/math.hpp

@@ -13,3 +13,4 @@
 #include <grit/math/sign.hpp>
 #include <grit/math/static_lookup_table.hpp>
 #include <grit/math/static_lookup_table_transform.hpp>
+#include <grit/math/trigonometry.hpp>

lib/grit/math/trigonometry.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <etl/cmath.hpp>
+#include <etl/numbers.hpp>
+
+namespace grit {
+
+/// \ingroup grit-math
+template<etl::floating_point Float>
+[[nodiscard]] constexpr auto bhaskara(Float x) -> Float
+{
+    auto const pi    = static_cast<Float>(etl::numbers::pi);
+    auto const num   = Float(16) * x * (pi - x);
+    auto const denom = Float(5) * pi * pi - Float(4) * x * (pi - x);
+    return num / denom;
+}
+
+}  // namespace grit

lib/grit/math/trigonometry_test.cpp

@@ -0,0 +1,15 @@
+#include "trigonometry.hpp"
+
+#include <catch2/catch_template_test_macros.hpp>
+#include <catch2/matchers/catch_matchers_floating_point.hpp>
+
+TEMPLATE_TEST_CASE("math: bhaskara", "", float, double)
+{
+    using Float = TestType;
+
+    REQUIRE_THAT(grit::bhaskara(Float(0.0)), Catch::Matchers::WithinAbs(0.0, 1e-8));
+    REQUIRE_THAT(grit::bhaskara(Float(0.5)), Catch::Matchers::WithinAbs(0.479426, 1e-2));
+    REQUIRE_THAT(grit::bhaskara(Float(1.0)), Catch::Matchers::WithinAbs(0.841471, 1e-2));
+    REQUIRE_THAT(grit::bhaskara(Float(etl::numbers::pi / 3.0)), Catch::Matchers::WithinAbs(0.866025, 1e-2));
+    REQUIRE_THAT(grit::bhaskara(Float(etl::numbers::pi / 2.0)), Catch::Matchers::WithinAbs(1.0, 1e-8));
+}