},
	)
	// PodStartSLIDuration is a Histogram that tracks the duration (in seconds) it takes for a single pod to run,
	// excluding the time for image pulling. This metric should reflect the "Pod startup latency SLI" definition
	// ref: https://github.com/kubernetes/community/blob/master/sig-scalability/slos/pod_startup_latency.md
	//

        context->template eigen_device<CPUDevice>()) = input_flat.maximum();

    // Calculate histogram statistics.
    const int32_t num_bins = calib_opts_.calibration_parameters().num_bins();
    Tensor* histogram_output = nullptr;
    OP_REQUIRES_OK(context, context->allocate_output("histogram", {num_bins},
                                                     &histogram_output));
    if (num_bins > 0) {

    CALIBRATION_METHOD_AVERAGE_MIN_MAX = 2;
    // Use the min/max percentile value of histogram.
    CALIBRATION_METHOD_HISTOGRAM_PERCENTILE = 3;
    // Use the histogram mid values that minimize MSE error.
    // This is very slow algorithm because it computes all errors for all
    // histogram mid value pairs. Therefore the value of num_bins is recommended
    // to be 256 or less.

        	# TYPE apiextensions_apiserver_validation_ratcheting_seconds histogram
        	apiextensions_apiserver_validation_ratcheting_seconds_bucket{le="1e-05"} 5
        	apiextensions_apiserver_validation_ratcheting_seconds_bucket{le="4e-05"} 5

                               const int32_t num_bins) {
  const float raw_bin_width = (max_value - min_value) / num_bins;
  return std::pow(2, std::ceil(std::log2(raw_bin_width)));
}

// Calculates the lower bound of the histogram. The lower bound is in form of
// `N * bin_width`.
inline float CalculateLowerBound(const float min_value, const float bin_width) {
  return std::floor(min_value / bin_width) * bin_width;
}

Regions are grouped by the region type and the point at which the region started.
The rightmost column of the table contains a latency histogram for each region group.
Note that this histogram only counts regions that began and ended within the traced
period.
However, the "Count" column includes all regions, including those that only started
or ended during the traced period.

import org.opensearch.search.aggregations.bucket.global.GlobalAggregationBuilder;
import org.opensearch.search.aggregations.bucket.histogram.DateHistogramAggregationBuilder;
import org.opensearch.search.aggregations.bucket.histogram.HistogramAggregationBuilder;
import org.opensearch.search.aggregations.bucket.missing.MissingAggregationBuilder;

    // The unique id of this `CustomAggregator` op.
    StrAttr:$id,
    // The integer value of the enforcing `CalibrationMethod`.
    I32Attr:$calibration_method,
    // The number of histogram bins.
    I32Attr:$num_bins,
    // Min percentile to be included in the selected range, only used in the
    // `HISTOGRAM_PERCENTILE` method.
    F32Attr:$min_percentile,

var (
	graphActionsDuration = metrics.NewHistogramVec(
		&metrics.HistogramOpts{
			Subsystem:      nodeAuthorizerSubsystem,
			Name:           "graph_actions_duration_seconds",
			Help:           "Histogram of duration of graph actions in node authorizer.",
			StabilityLevel: metrics.ALPHA,
			// Start with 0.1ms with the last bucket being [~200ms, Inf)
			Buckets: metrics.ExponentialBuckets(0.0001, 2, 12),
		},

	// Insert random uniforms and check histogram mass and
	// cumulative sum approximations.
	rnd := rand.New(rand.NewSource(42))
	mass := 0.0
	var mud mud
	for i := 0; i < 100; i++ {
		area, l, r := rnd.Float64(), rnd.Float64(), rnd.Float64()
		if rnd.Intn(10) == 0 {
			r = l
		}
		t.Log(l, r, area)
		mud.add(l, r, area)
		mass += area

		// Check total histogram weight.
		hmass := 0.0