1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // <valarray>
10 
11 // template<class T> class valarray;
12 
13 // template<class T>
14 //   valarray<T>
15 //   atan2(const valarray<T>& x, const valarray<T>& y);
16 
17 #include <valarray>
18 #include <cassert>
19 #include <sstream>
20 #include <cstddef>
21 
22 bool is_about(double x, double y, int p)
23 {
24     std::ostringstream o;
25     o.precision(p);
26     scientific(o);
27     o << x;
28     std::string a = o.str();
29     o.str("");
30     o << y;
31     return a == o.str();
32 }
33 
34 int main(int, char**)
35 {
36     {
37         typedef double T;
38         T a1[] = {-.9, -.5, 0., .5, .75};
39         T a2[] = {-.8,  .25, 0.375, -.5, .75};
40         T a3[] = {-2.2974386674766221e+00,
41                   -1.1071487177940904e+00,
42                    0.0000000000000000e+00,
43                    2.3561944901923448e+00,
44                    7.8539816339744828e-01};
45         const unsigned N = sizeof(a1)/sizeof(a1[0]);
46         std::valarray<T> v1(a1, N);
47         std::valarray<T> v2(a2, N);
48         std::valarray<T> v3 = atan2(v1, v2);
49         assert(v3.size() == v1.size());
50         for (std::size_t i = 0; i < v3.size(); ++i)
51             assert(is_about(v3[i], a3[i], 10));
52     }
53 
54   return 0;
55 }
56