VECTOR COMPUTATION

COMPUTER OR GANIZATION AND ARCHITECTURE DESIGNING FOR PERFORMANCE NINTH EDITION

Although the performance of mainframe general-purpose computers continues to
improve relentlessly, there continue to be applications that are beyond the reach of
the contemporary mainframe. There is a need for computers to solve mathematical
problems of physical processes, such as occur in disciplines including aerodynamics,
seismology, meteorology, and atomic, nuclear, and plasma physics.
Typically, these problems are characterized by the need for high precision
and a program that repetitively performs floating-point arithmetic operations on
large arrays of numbers. Most of these problems fall into the category known as
continuous-field simulation. In essence, a physical situation can be described by a
surface or region in three dimensions (e.g., the flow of air adjacent to the surface
of a rocket). This surface is approximated by a grid of points. A set of differential
equations defines the physical behavior of the surface at each point. The equations
are represented as an array of values and coefficients, and the solution involves
repeated arithmetic operations on the arrays of data.
Supercomputers were developed to handle these types of problems. These
machines are typically capable of billions of floating-point operations per second. In
contrast to mainframes, which are designed for multiprogramming and intensive I/O,
the supercomputer is optimized for the type of numerical calculation just described.
The supercomputer has limited use and, because of its price tag, a limited
market. Comparatively few of these machines are operational, mostly at research
centers and some government agencies with scientific or engineering functions. As
with other areas of computer technology, there is a constant demand to increase the
performance of the supercomputer. Thus, the technology and performance of the
supercomputer continues to evolve.
There is another type of system that has been designed to address the need for
vector computation, referred to as the array processor. Although a supercomputer
is optimized for vector computation, it is a general-purpose computer, capable of
handling scalar processing and general data processing tasks. Array processors do
not include scalar processing; they are configured as peripheral devices by both
mainframe and minicomputer users to run the vectorized portions of programs.