y = Complex(scope_, x, x);
        break;
      case ANGLE:
        y = Angle(scope_, x);
        break;
      case LGAMMA:
        y = Lgamma(scope_, x);
        break;
      case ERF:
        y = Erf(scope_, x);
        break;
      case ERFINV:
        y = Erfinv(scope_, x);
        break;
      case NDTRI:
        y = Ndtri(scope_, x);
        break;
    }

    float max_error;

	// all sums inside those bounds with 99% probability.
	N := n * hashSize
	var c float64
	// find c such that Prob(mean-c*stddev < x < mean+c*stddev)^N > .9999
	for c = 0.0; math.Pow(math.Erf(c/math.Sqrt(2)), float64(N)) < .9999; c += .1 {
	}
	c *= 11.0 // allowed slack: 40% to 60% - we don't need to be perfectly random
	mean := .5 * REP
	stddev := .5 * math.Sqrt(REP)
	low := int(mean - c*stddev)

	// all sums inside those bounds with 99% probability.
	N := n * hashSize
	var c float64
	// find c such that Prob(mean-c*stddev < x < mean+c*stddev)^N > .9999
	for c = 0.0; math.Pow(math.Erf(c/math.Sqrt(2)), float64(N)) < .9999; c += .1 {
	}
	c *= 11.0 // allowed slack: 40% to 60% - we don't need to be perfectly random
	mean := .5 * REP
	stddev := .5 * math.Sqrt(REP)
	low := int(mean - c*stddev)

		ch <- 1
	}()
	go func() {
		y = z
		ch <- 1
	}()
	<-ch
	<-ch
}

// May crash if the instrumentation is reckless.
func TestNoRaceEnoughRegisters(t *testing.T) {
	// from erf.go
	const (
		sa1 = 1
		sa2 = 2
		sa3 = 3
		sa4 = 4
		sa5 = 5
		sa6 = 6
		sa7 = 7
		sa8 = 8
	)
	var s, S float64
	s = 3.1415