# Communications of the ACM

#### Time-sharing and batch-processing: an experimental comparison of their values in a problem-solving situation

An experimental comparison of problem-solving using time-sharing and batch-processing computer systems conducted at MIT is described in this paper. This study is the first known attempt to evaluate two such systems for what may …

#### A note on reliable full-duplex transmission over half-duplex links

A simple procedure for achieving reliable full-duplex transmission over half-duplex links is proposed. The scheme is compared with another of the same type, which has recently been described in the literature. Finally, some comments …

#### Automated printed circuit routing with a stepping aperture

A computer program for routing interconnections on a two-sided printed circuit board with a regular pattern of lines, pins (terminals), and vias (feed-through holes) is described. In this program, each interconnection is given …

#### The simplex method of linear programming using LU decomposition

Standard computer implementations of Dantzig's simplex method for linear programming are based upon forming the inverse of the basic matrix and updating the inverse after every step of the method. These implementations have bad …

#### Rough and ready error estimates in Gaussian integration of analytic functions

Two expressions are derived for use in estimating the error in the numerical integration of analytic functions in terms of the maximum absolute value of the function in an appropriate region of regularity. These expressions are …

#### Chebyshev interpolation and quadrature formulas of very high degree

All the zeros x2m,i, i = 1(1)2m, of the Chebyshev polynomials T2m(x), m = 0(1)n, are found recursively just by taking n2n-1 real square roots. For interpolation or integration of ƒ(x), given ƒ(x2m,i), only x2m,i is needed tom …

#### An automatic grading scheme for simple programming exercises

A discussion is given of alterations that were made to a typical university operating system to record the results of programming exercises in three different languages, includeing assembly language. In this computer-controlled …

#### Dynamic space-sharing in computer systems

A formalization of relationships between space-sharing, program behavior, and processor efficiency in computer systems is presented. Concepts of value and cost of space allocation per task are defined and then value and cost  …

#### Clarification of Fortran standards—initial progress

In 1966, after four years of effort, FORTRAN became the first programming language standardized in the United States. Since that intital achievement, study and application of the standard specifications have revealed the need …