31.01.2018 Paolo Bientinesi (RWTH Aachen)

Teaching computers linear algebra

DLS_WS_17-18_BientinesiIn the mid 1950s, the computing world was revolutionized by the advent of "The IBM Mathematical Formula Translating System" (FORTRAN), a program--nowadays universally recognized as the first complete compiler--that allowed scientists to express calculations in a "high-level", portable language. Both FORTRAN and C were, and still are, much better solutions than computer-specific code, but they still require users to reduce their mathematical formulas to scalar computations. Indeed, computers only operate on scalars and small arrays, while scientists operate with vectors, matrices and higher-dimensional objects. In the past 60 years there has been tremendous progress in the world of programming languages and compilers, and many languages and libraries (Matlab, Julia, Armadillo, Eigen, ...) now make it possible to code directly in terms of matrices; however in terms of efficiency, these solutions are still far from what human experts achieve. In a nutshell, none of these tools know linear algebra well enough to compete with humans. In this talk I present the Linear Algebra Mapping Problem (LAMP), that is, how to efficiently compute linear algebra expressions from a set of available building blocks, and the compiler Linnea, our initial solution to the problem.