This paper compares the parallel efficiency of three Gram-Schmidt orthonorm
alization algorithms: modified Gram-Schmidt, classical Gram-Schmidt, and it
erated classical Gram-Schmidt. The paper shows how these algorithms can be
implemented on a parallel computer, and how their communication overhead ca
n be minimized. In addition, it briefly examines the numerical properties o
f these algorithms. Finally, it provides some guidelines for selecting the
most appropriate algorithm. Copyright (C) 2000 John Wiley & Sons, Ltd.