Source file src/pkg/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	//   [email protected]
    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	}