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# Source file src/math/cmplx/exp.go

```     1	// Copyright 2010 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 cmplx
6
7	import "math"
8
9	// The original C code, the long comment, and the constants
10	// below are from http://netlib.sandia.gov/cephes/c9x-complex/clog.c.
11	// The go code is a simplified version of the original C.
12	//
13	// Cephes Math Library Release 2.8:  June, 2000
14	// Copyright 1984, 1987, 1989, 1992, 2000 by Stephen L. Moshier
15	//
16	// The readme file at http://netlib.sandia.gov/cephes/ says:
17	//    Some software in this archive may be from the book _Methods and
18	// Programs for Mathematical Functions_ (Prentice-Hall or Simon & Schuster
19	// International, 1989) or from the Cephes Mathematical Library, a
20	// commercial product. In either event, it is copyrighted by the author.
21	// What you see here may be used freely but it comes with no support or
22	// guarantee.
23	//
24	//   The two known misprints in the book are repaired here in the
25	// source listings for the gamma function and the incomplete beta
26	// integral.
27	//
28	//   Stephen L. Moshier
29	//   moshier@na-net.ornl.gov
30
31	// Complex exponential function
32	//
33	// DESCRIPTION:
34	//
35	// Returns the complex exponential of the complex argument z.
36	//
37	// If
38	//     z = x + iy,
39	//     r = exp(x),
40	// then
41	//     w = r cos y + i r sin y.
42	//
43	// ACCURACY:
44	//
45	//                      Relative error:
46	// arithmetic   domain     # trials      peak         rms
47	//    DEC       -10,+10      8700       3.7e-17     1.1e-17
48	//    IEEE      -10,+10     30000       3.0e-16     8.7e-17
49
50	// Exp returns e**x, the base-e exponential of x.
51	func Exp(x complex128) complex128 {
52		r := math.Exp(real(x))
53		s, c := math.Sincos(imag(x))
54		return complex(r*c, r*s)
55	}
56
```

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