Criteria for transportable ALGOL libraries

Abstract

A rather comprehensive numerical software library (NUMAL {3}) was transported from a Philips EL-X8 computer to a CDC CYBER system. The experiences justify the following conclusion: If (I) we use a well-defined language (e.g., ALGOL 60 or ALGOL 68), if (2) we construct well-programmed software in that language, if (3) we have a good compiler and if (4) the computer/compiler has well-designed arithmetic properties, then the transportability problem scarcely exists. This statement can also be put the other way. The requirement of orthogonality of the conditions (I) - (4) determines what can be considered as a decent programming language, a good compiler, good programming and well-behaved arithmetic. For instance, good programming should not make use (perhaps at the cost of some efficiency) of idiosyncratic features of a language dialect, of a particular compiler or of a particular kind of machine arithmetic. From this abstract point of view, a number of useful properties of a well-structured portable software library are mentioned.