Adding upstream version 1.20.14.upstream/1.20.14upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 221 insertions, 0 deletions

diff --git a/src/math/cmplx/asin.go b/src/math/cmplx/asin.go
new file mode 100644
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--- /dev/null
+++ b/src/math/cmplx/asin.go
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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 circular arc sine
+//
+// DESCRIPTION:
+//
+// Inverse complex sine:
+//                               2
+// w = -i clog( iz + csqrt( 1 - z ) ).
+//
+// casin(z) = -i casinh(iz)
+//
+// ACCURACY:
+//
+//                      Relative error:
+// arithmetic   domain     # trials      peak         rms
+//    DEC       -10,+10     10100       2.1e-15     3.4e-16
+//    IEEE      -10,+10     30000       2.2e-14     2.7e-15
+// Larger relative error can be observed for z near zero.
+// Also tested by csin(casin(z)) = z.
+
+// Asin returns the inverse sine of x.
+func Asin(x complex128) complex128 {
+	switch re, im := real(x), imag(x); {
+	case im == 0 && math.Abs(re) <= 1:
+		return complex(math.Asin(re), im)
+	case re == 0 && math.Abs(im) <= 1:
+		return complex(re, math.Asinh(im))
+	case math.IsNaN(im):
+		switch {
+		case re == 0:
+			return complex(re, math.NaN())
+		case math.IsInf(re, 0):
+			return complex(math.NaN(), re)
+		default:
+			return NaN()
+		}
+	case math.IsInf(im, 0):
+		switch {
+		case math.IsNaN(re):
+			return x
+		case math.IsInf(re, 0):
+			return complex(math.Copysign(math.Pi/4, re), im)
+		default:
+			return complex(math.Copysign(0, re), im)
+		}
+	case math.IsInf(re, 0):
+		return complex(math.Copysign(math.Pi/2, re), math.Copysign(re, im))
+	}
+	ct := complex(-imag(x), real(x)) // i * x
+	xx := x * x
+	x1 := complex(1-real(xx), -imag(xx)) // 1 - x*x
+	x2 := Sqrt(x1)                       // x2 = sqrt(1 - x*x)
+	w := Log(ct + x2)
+	return complex(imag(w), -real(w)) // -i * w
+}
+
+// Asinh returns the inverse hyperbolic sine of x.
+func Asinh(x complex128) complex128 {
+	switch re, im := real(x), imag(x); {
+	case im == 0 && math.Abs(re) <= 1:
+		return complex(math.Asinh(re), im)
+	case re == 0 && math.Abs(im) <= 1:
+		return complex(re, math.Asin(im))
+	case math.IsInf(re, 0):
+		switch {
+		case math.IsInf(im, 0):
+			return complex(re, math.Copysign(math.Pi/4, im))
+		case math.IsNaN(im):
+			return x
+		default:
+			return complex(re, math.Copysign(0.0, im))
+		}
+	case math.IsNaN(re):
+		switch {
+		case im == 0:
+			return x
+		case math.IsInf(im, 0):
+			return complex(im, re)
+		default:
+			return NaN()
+		}
+	case math.IsInf(im, 0):
+		return complex(math.Copysign(im, re), math.Copysign(math.Pi/2, im))
+	}
+	xx := x * x
+	x1 := complex(1+real(xx), imag(xx)) // 1 + x*x
+	return Log(x + Sqrt(x1))            // log(x + sqrt(1 + x*x))
+}
+
+// Complex circular arc cosine
+//
+// DESCRIPTION:
+//
+// w = arccos z  =  PI/2 - arcsin z.
+//
+// ACCURACY:
+//
+//                      Relative error:
+// arithmetic   domain     # trials      peak         rms
+//    DEC       -10,+10      5200      1.6e-15      2.8e-16
+//    IEEE      -10,+10     30000      1.8e-14      2.2e-15
+
+// Acos returns the inverse cosine of x.
+func Acos(x complex128) complex128 {
+	w := Asin(x)
+	return complex(math.Pi/2-real(w), -imag(w))
+}
+
+// Acosh returns the inverse hyperbolic cosine of x.
+func Acosh(x complex128) complex128 {
+	if x == 0 {
+		return complex(0, math.Copysign(math.Pi/2, imag(x)))
+	}
+	w := Acos(x)
+	if imag(w) <= 0 {
+		return complex(-imag(w), real(w)) // i * w
+	}
+	return complex(imag(w), -real(w)) // -i * w
+}
+
+// Complex circular arc tangent
+//
+// DESCRIPTION:
+//
+// If
+//     z = x + iy,
+//
+// then
+//          1       (    2x     )
+// Re w  =  - arctan(-----------)  +  k PI
+//          2       (     2    2)
+//                  (1 - x  - y )
+//
+//               ( 2         2)
+//          1    (x  +  (y+1) )
+// Im w  =  - log(------------)
+//          4    ( 2         2)
+//               (x  +  (y-1) )
+//
+// Where k is an arbitrary integer.
+//
+// catan(z) = -i catanh(iz).
+//
+// ACCURACY:
+//
+//                      Relative error:
+// arithmetic   domain     # trials      peak         rms
+//    DEC       -10,+10      5900       1.3e-16     7.8e-18
+//    IEEE      -10,+10     30000       2.3e-15     8.5e-17
+// The check catan( ctan(z) )  =  z, with |x| and |y| < PI/2,
+// had peak relative error 1.5e-16, rms relative error
+// 2.9e-17.  See also clog().
+
+// Atan returns the inverse tangent of x.
+func Atan(x complex128) complex128 {
+	switch re, im := real(x), imag(x); {
+	case im == 0:
+		return complex(math.Atan(re), im)
+	case re == 0 && math.Abs(im) <= 1:
+		return complex(re, math.Atanh(im))
+	case math.IsInf(im, 0) || math.IsInf(re, 0):
+		if math.IsNaN(re) {
+			return complex(math.NaN(), math.Copysign(0, im))
+		}
+		return complex(math.Copysign(math.Pi/2, re), math.Copysign(0, im))
+	case math.IsNaN(re) || math.IsNaN(im):
+		return NaN()
+	}
+	x2 := real(x) * real(x)
+	a := 1 - x2 - imag(x)*imag(x)
+	if a == 0 {
+		return NaN()
+	}
+	t := 0.5 * math.Atan2(2*real(x), a)
+	w := reducePi(t)
+
+	t = imag(x) - 1
+	b := x2 + t*t
+	if b == 0 {
+		return NaN()
+	}
+	t = imag(x) + 1
+	c := (x2 + t*t) / b
+	return complex(w, 0.25*math.Log(c))
+}
+
+// Atanh returns the inverse hyperbolic tangent of x.
+func Atanh(x complex128) complex128 {
+	z := complex(-imag(x), real(x)) // z = i * x
+	z = Atan(z)
+	return complex(imag(z), -real(z)) // z = -i * z
+}