panic("fail")
	}

	/* int32 */
	var ln1 int32 = +5
	var ln2 int32 = -5
	var ld1 int32 = +3
	var ld2 int32 = -3

	if ln1/ld1 != q1 || ln1%ld1 != r1 {
		println("int32-1", ln1, ld1, ln1/ld1, ln1%ld1)
		panic("fail")
	}
	if ln2/ld1 != q2 || ln2%ld1 != r2 {
		println("int32-2", ln2, ld1, ln2/ld1, ln2%ld1)
		panic("fail")
	}
	if ln1/ld2 != q3 || ln1%ld2 != r3 {

		println("ln 3", x)
		panic("fail")
	}
	if x := ln([]T{}); x != 1 {
		println("ln 1", x)
		panic("fail")
	}
	if x := ln2(nil, nil, nil); x != 2*3 {
		println("ln2 3", x)
		panic("fail")
	}
	if x := ln2([]T{}); x != 2*1 {
		println("ln2 1", x)
		panic("fail")
	}
	if x := ((*T)(nil)).Sum(1, 3, 5, 7); x != 16 {
		println("(*T)(nil).Sum", x)
		panic("fail")
	}

	if absx >= Ln2X56 { // if |x| >= 56 * ln2
		if sign {
			return -1 // x < -56*ln2, return -1
		}
		if absx >= Othreshold { // if |x| >= 709.78...
			return Inf(1)
		}
	}

	// argument reduction
	var c float64
	var k int
	if absx > Ln2Half { // if  |x| > 0.5 * ln2
		var hi, lo float64
		if absx < Ln2HalfX3 { // and |x| < 1.5 * ln2
			if !sign {
				hi = x - Ln2Hi
				lo = Ln2Lo

		iMath := MulByLog2Log10(x)
		fMath := int(math.Floor(float64(x) * math.Ln2 / math.Ln10))
		if iMath != fMath {
			t.Errorf("mulByLog2Log10(%d) failed: %d vs %d\n", x, iMath, fMath)
		}
	}
}

func TestMulByLog10Log2(t *testing.T) {
	for x := -500; x <= +500; x++ {
		iMath := MulByLog10Log2(x)
		fMath := int(math.Floor(float64(x) * math.Ln10 / math.Ln2))
		if iMath != fMath {

	return log2(x)
}

func log2(x float64) float64 {
	frac, exp := Frexp(x)
	// Make sure exact powers of two give an exact answer.
	// Don't depend on Log(0.5)*(1/Ln2)+exp being exactly exp-1.
	if frac == 0.5 {
		return float64(exp - 1)
	}
	return Log(frac)*(1/Ln2) + float64(exp)

			}
			t.Fatal(err)
		}

		ln2, err := FileListener(f)
		if err := f.Close(); err != nil {
			t.Error(err)
		}
		if err != nil {
			if perr := parseCommonError(err); perr != nil {
				t.Error(perr)
			}
			t.Fatal(err)
		}
		defer ln2.Close()

		var wg sync.WaitGroup
		wg.Add(1)
		go func() {
			defer wg.Done()
			c, err := Dial(ln2.Addr().Network(), ln2.Addr().String())

//
// This code is a simplified version of the original.

#define LN2 0.6931471805599453094172321214581766 // log_e(2)
#define LOG2E 1.4426950408889634073599246810018920 // 1/LN2
#define LN2U 0.69314718055966295651160180568695068359375 // upper half LN2
#define LN2L 0.28235290563031577122588448175013436025525412068e-12 // lower half LN2
#define PosInf 0x7FF0000000000000
#define NegInf 0xFFF0000000000000

//
//
// asinh(x)
// Method :
//	Based on
//	        asinh(x) = sign(x) * log [ |x| + sqrt(x*x+1) ]
//	we have
//	asinh(x) := x  if  1+x*x=1,
//	         := sign(x)*(log(x)+ln2) for large |x|, else
//	         := sign(x)*log(2|x|+1/(|x|+sqrt(x*x+1))) if|x|>2, else
//	         := sign(x)*log1p(|x| + x**2/(1 + sqrt(1+x**2)))
//

// Asinh returns the inverse hyperbolic sine of x.
//

	SqrtPhi = 1.27201964951406896425242246173749149171560804184009624861664038 // https://oeis.org/A139339

	Ln2    = 0.693147180559945309417232121458176568075500134360255254120680009 // https://oeis.org/A002162
	Log2E  = 1 / Ln2
	Ln10   = 2.30258509299404568401799145468436420760110148862877297603332790 // https://oeis.org/A002392
	Log10E = 1 / Ln10
)

// Floating-point limit values.

// is preserved.
// ====================================================
//
//
// __ieee754_acosh(x)
// Method :
//	Based on
//	        acosh(x) = log [ x + sqrt(x*x-1) ]
//	we have
//	        acosh(x) := log(x)+ln2,	if x is large; else
//	        acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x>2; else
//	        acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t=x-1.
//
// Special cases:
//	acosh(x) is NaN with signal if x<1.