name string
	in   float64 // used for error messages, not an input
	got  float64
	want float64
}{
	{"sqrt0", 0, math.Sqrt(0), 0},
	{"sqrt1", 1, math.Sqrt(1), 1},
	{"sqrt2", 2, math.Sqrt(2), math.Sqrt2},
	{"sqrt4", 4, math.Sqrt(4), 2},
	{"sqrt100", 100, math.Sqrt(100), 10},
	{"sqrt101", 101, math.Sqrt(101), 10.04987562112089},
}

var nanTests = [...]struct {
	name string

       */
      sqrt0 = sqrtApproxWithDoubles(x.shiftRight(shift)).shiftLeft(shift >> 1);
    }
    BigInteger sqrt1 = sqrt0.add(x.divide(sqrt0)).shiftRight(1);
    if (sqrt0.equals(sqrt1)) {
      return sqrt0;
    }
    do {
      sqrt0 = sqrt1;
      sqrt1 = sqrt0.add(x.divide(sqrt0)).shiftRight(1);
    } while (sqrt1.compareTo(sqrt0) < 0);
    return sqrt0;
  }

  @GwtIncompatible // TODO

       */
      sqrt0 = sqrtApproxWithDoubles(x.shiftRight(shift)).shiftLeft(shift >> 1);
    }
    BigInteger sqrt1 = sqrt0.add(x.divide(sqrt0)).shiftRight(1);
    if (sqrt0.equals(sqrt1)) {
      return sqrt0;
    }
    do {
      sqrt0 = sqrt1;
      sqrt1 = sqrt0.add(x.divide(sqrt0)).shiftRight(1);
    } while (sqrt1.compareTo(sqrt0) < 0);
    return sqrt0;
  }

  @GwtIncompatible // TODO

	uNeg := new(Element).Negate(u)
	correctSignSqrt := check.Equal(u)
	flippedSignSqrt := check.Equal(uNeg)
	flippedSignSqrtI := check.Equal(t0.Multiply(uNeg, sqrtM1))

	rPrime := new(Element).Multiply(rr, sqrtM1) // r_prime = SQRT_M1 * r
	// r = CT_SELECT(r_prime IF flipped_sign_sqrt | flipped_sign_sqrt_i ELSE r)
	rr.Select(rPrime, rr, flippedSignSqrt|flippedSignSqrtI)

func zero[T Complex]() T {
	return T(0)
}
func pi[T Complex]() T {
	return T(3.14)
}
func sqrtN1[T Complex]() T {
	return T(-1i)
}

func main() {
	fmt.Println(zero[complex128]())
	fmt.Println(pi[complex128]())
	fmt.Println(sqrtN1[complex128]())
	fmt.Println(zero[complex64]())
	fmt.Println(pi[complex64]())
	fmt.Println(sqrtN1[complex64]())

//	Log1p(x < -1) = NaN
//	Log1p(NaN) = NaN
func Log1p(x float64) float64 {
	if haveArchLog1p {
		return archLog1p(x)
	}
	return log1p(x)
}

func log1p(x float64) float64 {
	const (
		Sqrt2M1     = 4.142135623730950488017e-01  // Sqrt(2)-1 = 0x3fda827999fcef34
		Sqrt2HalfM1 = -2.928932188134524755992e-01 // Sqrt(2)/2-1 = 0xbfd2bec333018866
		Small       = 1.0 / (1 << 29)              // 2**-29 = 0x3e20000000000000

}

func TestDecimalConstants(t *testing.T) {
	sqrtM1String := "19681161376707505956807079304988542015446066515923890162744021073123829784752"
	if exp := new(Element).fromDecimal(sqrtM1String); sqrtM1.Equal(exp) != 1 {
		t.Errorf("sqrtM1 is %v, expected %v", sqrtM1, exp)
	}
	// d is in the parent package, and we don't want to expose d or fromDecimal.
	// dString := "37095705934669439343138083508754565189542113879843219016388785533085940283555"

(Div64F x (Const64F <t> [c])) && reciprocalExact64(c) => (Mul64F x (Const64F <t> [1/c]))

// rewrite single-precision sqrt expression "float32(math.Sqrt(float64(x)))"
(Cvt64Fto32F sqrt0:(Sqrt (Cvt32Fto64F x))) && sqrt0.Uses==1 => (Sqrt32 x)

(Sqrt (Const64F [c])) && !math.IsNaN(math.Sqrt(c)) => (Const64F [math.Sqrt(c)])

// for rewriting results of some late-expanded rewrites (below)

		return true
	}
	// match: (Cvt64Fto32F sqrt0:(Sqrt (Cvt32Fto64F x)))
	// cond: sqrt0.Uses==1
	// result: (Sqrt32 x)
	for {
		sqrt0 := v_0
		if sqrt0.Op != OpSqrt {
			break
		}
		sqrt0_0 := sqrt0.Args[0]
		if sqrt0_0.Op != OpCvt32Fto64F {
			break
		}
		x := sqrt0_0.Args[0]
		if !(sqrt0.Uses == 1) {
			break
		}
		v.reset(OpSqrt32)
		v.AddArg(x)

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