JaLA: a Java package for Linear Algebra

Abstract

While the Java language has taken the world by storm, it has left the scienti c computing community out in the cold. Java lacks the capability for multi-dimensional arrays that can be implemented e ciently, and more importantly, lacks the ability to use data layouts that are compatible with the wide variety of scienti c subroutine packages available, such as the BLAS [3], ESSL [2], LAPACK [1], and so on. The problems stems from the fact that in Java, every non-scalar data item is an object, and every object must have an object header, typically two or three words long. Two-dimensional arrays are vector objects that contain a list of vector objects corresponding to the second dimension. Such a data organization is incompatible with the data layouts used by FORTRAN and C. Data access is also inherently less e cient because an extra indirection is required and it is impossible to traverse the array using a simple increment scheme. Java also lacks the ability to represent sub-arrays of any sort, or the ability to pass an array element by reference. Unfortunately, Java's extension capabilities are not su cient to provide the necessary functionality with a convenient syntax. If the native capabilities of Java were used to declare array classes, then programmers would be required to write programs like this: