| class  | EstimatorBasicAvg | Basic average case estimator for matrix sparsity:
 sp = 1 - Math.pow(1-sp1*sp2, k) | 
| class  | EstimatorBasicWorst | Basic average case estimator for matrix sparsity:
 sp = Math.min(1, sp1 * k) * Math.min(1, sp2 * k). | 
| class  | EstimatorBitsetMM | This estimator implements a naive but rather common approach of boolean matrix
 multiplies which allows to infer the exact non-zero structure and thus is
 also useful for sparse result preallocation. | 
| class  | EstimatorDensityMap | This estimator implements an approach called density maps, as introduced in
 David Kernert, Frank Köhler, Wolfgang Lehner: SpMacho - Optimizing Sparse 
 Linear Algebra Expressions with Probabilistic Density Estimation. | 
| class  | EstimatorLayeredGraph | This estimator implements an approach based on a so-called layered graph,
 introduced in
 Edith Cohen. | 
| class  | EstimatorMatrixHistogram | This estimator implements a remarkably simple yet effective
 approach for incorporating structural properties into sparsity
 estimation. | 
| class  | EstimatorSample | This estimator implements an approach based on row/column sampling
 Yongyang Yu, MingJie Tang, Walid G. | 
| class  | EstimatorSampleRa | This estimator implements an approach based on row/column sampling
 
 Rasmus Resen Amossen, Andrea Campagna, Rasmus Pagh:
 Better Size Estimation for Sparse Matrix Products. |