[libc-commits] [libc] [libc][math][c23] Implement C23 math function atanpif16 (PR #150400)

[via libc-commits]

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@@ -0,0 +1,66 @@
+//===-- Unittests for atanpif16 -------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/errno/libc_errno.h"
+#include "src/math/atanpif16.h"
+#include "test/UnitTest/FPMatcher.h"
+
+using LlvmLibcAtanpif16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+TEST_F(LlvmLibcAtanpif16Test, SpecialNumbers) {
+  // zero
+  EXPECT_FP_EQ(zero, LIBC_NAMESPACE::atanpif16(zero));
+  EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::atanpif16(neg_zero));
+
+  // NaN inputs
+  EXPECT_FP_EQ(FPBits::quiet_nan().get_val(),
+               LIBC_NAMESPACE::atanpif16(FPBits::quiet_nan().get_val()));
+
+  EXPECT_FP_EQ(FPBits::quiet_nan().get_val(),
+               LIBC_NAMESPACE::atanpif16(FPBits::signaling_nan().get_val()));
+
+  // infinity inputs -> should return +/-0.5
+  EXPECT_FP_EQ(0.5f16, LIBC_NAMESPACE::atanpif16(inf));
+  EXPECT_FP_EQ(-0.5f16, LIBC_NAMESPACE::atanpif16(neg_inf));
+}
+
+TEST_F(LlvmLibcAtanpif16Test, SymmetryProperty) {
+  // Test that atanpi(-x) = -atanpi(x)
+  constexpr float16 TEST_VALS[] = {0.1f16,  0.25f16, 0.5f16,   0.75f16,
+                                   1.0f16,  1.5f16,  2.0f16,   5.0f16,
+                                   10.0f16, 50.0f16, 100.0f16, 1000.0f16};
+
+  for (float16 x : TEST_VALS) {
+    FPBits neg_x_bits(x);
+    neg_x_bits.set_sign(Sign::NEG);
+    float16 neg_x = neg_x_bits.get_val();
+
+    float16 pos_result = LIBC_NAMESPACE::atanpif16(x);
+    float16 neg_result = LIBC_NAMESPACE::atanpif16(neg_x);
+
+    EXPECT_FP_EQ(pos_result, FPBits(neg_result).abs().get_val());
+  }
+}
+
+TEST_F(LlvmLibcAtanpif16Test, MonotonicityProperty) {
+  // Test that atanpi is monotonically increasing
+  constexpr float16 TEST_VALS[] = {-1000.0f16, -100.0f16, -10.0f16, -2.0f16,
+                                   -1.0f16,    -0.5f16,   -0.1f16,  0.0f16,
+                                   0.1f16,     0.5f16,    1.0f16,   2.0f16,
+                                   10.0f16,    100.0f16,  1000.0f16};
+
+  for (size_t i = 0; i < sizeof(TEST_VALS) / sizeof(TEST_VALS[0]) - 1; ++i) {
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overmighty wrote:

You could (should?) use `LIBC_NAMESPACE::cpp::array` instead of resorting to `sizeof(TEST_VALS) / sizeof(TEST_VALS[0])`.

https://github.com/llvm/llvm-project/pull/150400