**A combined unifrontal/multifrontal method for unsymmetric sparse matrices**

Timothy A. Davis, Iain S. Duff

Pages: 1-20

DOI: 10.1145/305658.287640

We discuss the organization of frontal matrices in multifrontal methods for the solution of large sparse sets of unsymmetric linear equations. In the multifrontal method, work on a frontal matrix can be suspended, the frontal matrix can be...

**A test package for Sturm-Liouville solvers**

J. D. Pryce

Pages: 21-57

DOI: 10.1145/305658.287651

The author and colleagues have produced a collection of 60 test problems which offer a realistic performance test of the currently available automatic codes for eigenvalues of the classical Sturm-Liouville problem. We describe a Fortran...

**Algorithm 789: SLTSTPAK**: a test package for Sturm-Liouville solvers

J. D. Pryce

Pages: 58-69

DOI: 10.1145/305658.287652

We give technical details of the Sturm-Liouville test package SLTSTPAK, complementing the companion article (this issue) on its design. SLTSTPAK comprises the follwing : a specification of how to write a routine TSTSET containing a set of...

**Algorithm 790: CSHEP2D**: cubic Shepard method for bivariate interpolation of scattered data

Robert J. Renka

Pages: 70-73

DOI: 10.1145/305658.305737

We describe a new algorithm for scattered data interpolation. The method is similar to that of Algorithm 660 but achieves cubic precision and C2 continuity at very little additional cost. An accompanying...

**Algorithm 791: TSHEP2D**: cosine series Shepard method for bivariate interpolation of scattered data

Robert J. Renka, Ron Brown

Pages: 74-77

DOI: 10.1145/305658.305754

We describe a new algorithm for scattered data interpolation. It is based on a modified Shepard method similar to that of Algorithm 660 but uses 10-parameter cosine series nodal functions in place of quadratic polynomials. Also, the interpolant...

**Algorithm 792**: accuracy test of ACM algorithms for interpolation of scattered data in the plane

Robert J. Renka, Ron Brown

Pages: 78-94

DOI: 10.1145/305658.305745

We present results of accuracy tests on scattered-data fitting methods that have been published as ACM algorithms. The algorithms include seven triangulation-based methods and three modified Shepard methods, two of which are new algorithms. Our...

**Remark on Algorithm 716**

F. J. Testa, Robert J. Renka

Pages: 95-96

DOI: 10.1145/305658.287656

The curve-fitting package TSPACK has been converted to double precision. Also, portability has been improved by eliminating some potential errors.

**Remark on Algorithm 751**

Robert J. Renka

Pages: 97-98

DOI: 10.1145/305658.305726

The triangulation package TRIPACK has been revised to run more efficiently and to eliminate some potential errors. Also, a portable triangulation plotting routine was added.

**Remark on Algorithm 752**

Robert J. Renka

Pages: 99-100

DOI: 10.1145/305658.305731

The triangulation-based scatterd-data fitting package SRFPACK was updated for (a) compatibility with a revised interface to the triangulation package TRIPACK, (b) the elimination of potential errors in the treatment of tension factors and in the...

**A note on the recursive calculation of incomplete gamma functions**

Walter Gautschi

Pages: 101-107

DOI: 10.1145/305658.305717

It is known that the recurrence relation for incomplete gamma functions {&ggr;(a + n, x)}, 0 ≤ a < 1, n = 0, 1, 2 ..., when x is...

**Remark on Algorithm 702—the updated truncated Newton minimization package**

Dexuan Xie, Tamar Schlick

Pages: 108-122

DOI: 10.1145/305658.305698

A truncated Newton minimization package, TNPACK, was described in ACM Transactions on Mathematical Software 14, 1 (Mar. 1992), pp.46–111. Modifications to enhance performance, especially for large-scale minimization of...

**Self-adapting Fortran 77 machine constants**: comment on Algorithm 528

David M. Gay, Eric Grosse

Pages: 123-126

DOI: 10.1145/305658.305711

This note discusses user dissatisfaction with the need to uncomment data statements in Algorithm 528, comments on alternative approaches tried by the community, and proposes a solution that is both automatic and safe.