OpenCores
URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [math/] [atan2.go] - Blame information for rev 848

Go to most recent revision | Details | Compare with Previous | View Log

Line No. Rev Author Line
1 747 jeremybenn 
// Copyright 2009 The Go Authors. All rights reserved.
2 
// Use of this source code is governed by a BSD-style
3 
// license that can be found in the LICENSE file.
4 
 
5 
package math
6 
 
7 
// Atan2 returns the arc tangent of y/x, using
8 
// the signs of the two to determine the quadrant
9 
// of the return value.
10 
//
11 
// Special cases are (in order):
12 
//      Atan2(y, NaN) = NaN
13 
//      Atan2(NaN, x) = NaN
14 
//      Atan2(+0, x>=0) = +0
15 
//      Atan2(-0, x>=0) = -0
16 
//      Atan2(+0, x<=-0) = +Pi
17 
//      Atan2(-0, x<=-0) = -Pi
18 
//      Atan2(y>0, 0) = +Pi/2
19 
//      Atan2(y<0, 0) = -Pi/2
20 
//      Atan2(+Inf, +Inf) = +Pi/4
21 
//      Atan2(-Inf, +Inf) = -Pi/4
22 
//      Atan2(+Inf, -Inf) = 3Pi/4
23 
//      Atan2(-Inf, -Inf) = -3Pi/4
24 
//      Atan2(y, +Inf) = 0
25 
//      Atan2(y>0, -Inf) = +Pi
26 
//      Atan2(y<0, -Inf) = -Pi
27 
//      Atan2(+Inf, x) = +Pi/2
28 
//      Atan2(-Inf, x) = -Pi/2
29 
 
30 
//extern atan2
31 
func libc_atan2(float64, float64) float64
32 
 
33 
func Atan2(y, x float64) float64 {
34 
        return libc_atan2(y, x)
35 
}
36 
 
37 
func atan2(y, x float64) float64 {
38 
        // special cases
39 
        switch {
40 
        case IsNaN(y) || IsNaN(x):
41 
                return NaN()
42 
        case y == 0:
43 
                if x >= 0 && !Signbit(x) {
44 
                        return Copysign(0, y)
45 
                }
46 
                return Copysign(Pi, y)
47 
        case x == 0:
48 
                return Copysign(Pi/2, y)
49 
        case IsInf(x, 0):
50 
                if IsInf(x, 1) {
51 
                        switch {
52 
                        case IsInf(y, 0):
53 
                                return Copysign(Pi/4, y)
54 
                        default:
55 
                                return Copysign(0, y)
56 
                        }
57 
                }
58 
                switch {
59 
                case IsInf(y, 0):
60 
                        return Copysign(3*Pi/4, y)
61 
                default:
62 
                        return Copysign(Pi, y)
63 
                }
64 
        case IsInf(y, 0):
65 
                return Copysign(Pi/2, y)
66 
        }
67 
 
68 
        // Call atan and determine the quadrant.
69 
        q := Atan(y / x)
70 
        if x < 0 {
71 
                if q <= 0 {
72 
                        return q + Pi
73 
                }
74 
                return q - Pi
75 
        }
76 
        return q
77 
}

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.