[libc][math] Update range.

Author: harrisonGPU

libc/test/src/math/atanhf16_test.cpp

@@ -17,21 +17,24 @@
 using LlvmLibcAtanhf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
 namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
 
+// Range for positive numbers: [0, 1)
 static constexpr uint16_t POS_START = 0x0000U;
-static constexpr uint16_t POS_STOP = 0x3BFFU;
+static constexpr uint16_t POS_STOP = 0x3C00;
+
+// Range for negative numbers: (-1, 0]
 static constexpr uint16_t NEG_START = 0xBBFFU;
 static constexpr uint16_t NEG_STOP = 0x8000U;
 
 TEST_F(LlvmLibcAtanhf16Test, PositiveRange) {
-  for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
+  for (uint16_t v = POS_START; v < POS_STOP; ++v) {
     float16 x = FPBits(v).get_val();
     EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Atanh, x,
                                    LIBC_NAMESPACE::atanhf16(x), 0.5);
   }
 }
 
 TEST_F(LlvmLibcAtanhf16Test, NegativeRange) {
-  for (uint16_t v = NEG_START; v <= NEG_STOP; --v) {
+  for (uint16_t v = NEG_START; v >= NEG_STOP; --v) {
     float16 x = FPBits(v).get_val();
     EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Atanh, x,
                                    LIBC_NAMESPACE::atanhf16(x), 0.5);