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// Copyright 2010 The Go Authors. All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

package cmplx

import "math"

// The original C code, the long comment, and the constants

// below are from http://netlib.sandia.gov/cephes/c9x-complex/clog.c.

// The go code is a simplified version of the original C.

//

// Cephes Math Library Release 2.8:  June, 2000

// Copyright 1984, 1987, 1989, 1992, 2000 by Stephen L. Moshier

//

// The readme file at http://netlib.sandia.gov/cephes/ says:

//    Some software in this archive may be from the book _Methods and

// Programs for Mathematical Functions_ (Prentice-Hall or Simon & Schuster

// International, 1989) or from the Cephes Mathematical Library, a

// commercial product. In either event, it is copyrighted by the author.

// What you see here may be used freely but it comes with no support or

// guarantee.

//

//   The two known misprints in the book are repaired here in the

// source listings for the gamma function and the incomplete beta

// integral.

//

//   Stephen L. Moshier

//   moshier@na-net.ornl.gov

// Complex exponential function

//

// DESCRIPTION:

//

// Returns the complex exponential of the complex argument z.

//

// If

//     z = x + iy,

//     r = exp(x),

// then

//     w = r cos y + i r sin y.

//

// ACCURACY:

//

//                      Relative error:

// arithmetic   domain     # trials      peak         rms

//    DEC       -10,+10      8700       3.7e-17     1.1e-17

//    IEEE      -10,+10     30000       3.0e-16     8.7e-17

// Exp returns e**x, the base-e exponential of x.

func Exp(x complex128) complex128 {

        r := math.Exp(real(x))

        s, c := math.Sincos(imag(x))

        return complex(r*c, r*s)

}