variance method

double variance()

Variance of all elements.

Computes the variance (average squared deviation from mean).

Example:

var arr = NDArray([[1, 2, 3], [4, 5, 6]]);
print(arr.variance()); // ≈ 2.917

// Relationship: variance = std^2
var std = arr.std();
var variance = std * std; // Same as arr.variance()

Implementation

double variance() {
  final m = mean();
  num sumSquaredDiff = 0;
  _iterateAll((value) {
    final diff = (value as num) - m;
    sumSquaredDiff += diff * diff;
  });
  return sumSquaredDiff / size;
}