2  * Single-precision scalar atan2(x) function.
4  * Copyright (c) 2021-2024, Arm Limited.
5  * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
17 #define PiOver4 (0x1.921fb6p-1f)
23    d for which P underflows, and is used to special-case such inputs.  */
33       /* Subnormal case - we still need to get the exponent right for subnormal  in biased_exponent()
35       return ex - __builtin_clz (fi << 9);  in biased_exponent()
41    2.88ulps in [99.0, 101.0] x [99.0, 101.0]:
42    atan2f(0x1.9332d8p+6, 0x1.8cb6c4p+6) got 0x1.964646p-1
43 				       want 0x1.964640p-1.  */
45 atan2f (float y, float x)  in atan2f()  argument
47   uint32_t ix = asuint (x);  in atan2f()
56   /* x or y is NaN.  */  in atan2f()
58     return x + y;  in atan2f()
60   /* m = 2 * sign(x) + sign(y).  */  in atan2f()
64      that we do not use +-tiny shifts (non-nearest rounding mode).  */  in atan2f()
66   int32_t exp_diff = biased_exponent (x) - biased_exponent (y);  in atan2f()
68   /* Special case for (x, y) either on or very close to the x axis. Either y =  in atan2f()
69      0, or y is tiny and x is huge (difference in exponents >=  in atan2f()
71      case when x is negative (i.e. quadrants 2 or 3).  */  in atan2f()
78 	  return y; /* atan(+-0,+anything)=+-0.  */  in atan2f()
80 	  return Pi; /* atan(+0,-anything) = pi.  */  in atan2f()
82 	  return -Pi; /* atan(-0,-anything) =-pi.  */  in atan2f()
85   /* Special case for (x, y) either on or very close to the y axis. Either x =  in atan2f()
86      0, or x is tiny and y is huge (difference in exponents >=  in atan2f()
88   if (unlikely (iax == 0 || exp_diff <= -POLY_UFLOW_BOUND))  in atan2f()
89     return sign_y ? -PiOver2 : PiOver2;  in atan2f()
91   /* x is INF.  */  in atan2f()
101 	      return -PiOver4; /* atan(-INF,+INF).  */  in atan2f()
103 	      return 3.0f * PiOver4; /* atan(+INF,-INF).  */  in atan2f()
105 	      return -3.0f * PiOver4; /* atan(-INF,-INF).  */  in atan2f()
115 	      return -0.0f; /* atan(-...,+INF).  */  in atan2f()
117 	      return Pi; /* atan(+...,-INF).  */  in atan2f()
119 	      return -Pi; /* atan(-...,-INF).  */  in atan2f()
125     return sign_y ? -PiOver2 : PiOver2;  in atan2f()
135   float n = pred_aygtax ? -ax : ay;  in atan2f()
142       /* If (x, y) is very close to x axis and x is positive, the polynomial  in atan2f()
149       float shift = sign_x ? -2.0f : 0.0f;  in atan2f()
156   /* Account for the sign of x and y.  */  in atan2f()
163 TEST_INTERVAL (atan2f, -10.0, 10.0, 50000)
164 TEST_INTERVAL (atan2f, -1.0, 1.0, 40000)