The SPQR RANK package contains routines that calculate the numerical rank of large, sparse, numerically rank-deficient matrices. The routines can also calculate orthonormal bases for numerical null spaces, approximate pseudoinverse solutions to least squares problems involving rankdeficient matrices, and basic solutions to these problems. The algorithms are based on SPQR from SuiteSparseQR (ACM...

We consider the problem of commutative rank computation of a given matrix space, B ⊆ Fn×n. The problem is fundamental, as it generalizes several computational problems from algebra and combinatorics. For instance, checking if the commutative rank of the space is n, subsumes problems such as testing perfect matching in graphs and identity testing of algebraic branching programs. An efficient det...

We consider a variant of Heilbronn’s triangle problem by asking for fixed integers d, k ≥ 2 and any integer n ≥ k for a distribution of n points in the d-dimensional unit cube [0, 1] such that the minimum volume of the convex hull of k points among these n points is as large as possible. We show that there exists a configuration of n points in [0, 1], such that, simultaneously for j = 2, . . . ...

This paper is concerned with the fast computation of Fourier integral operators of the general form ∫ Rd e f(k)dk, where k is a frequency variable, Φ(x, k) is a phase function obeying a standard homogeneity condition, and f is a given input. This is of interest for such fundamental computations are connected with the problem of finding numerical solutions to wave equations, and also frequently ...