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AviationTest Facilities, Equipment and Methods

Fast Random Projections Using Lean Walsh Transforms

Authors: Edo Liberty; Nir Ailon; Amit Singer; YALE UNIV NEW HAVEN CT DEPT OF COMPUTER SCIENCE
Abstract:
We present a kappa * d random projection matrix that is applicable to vectors chi epsilon R(exp d) in O(d) operations if d >kappa(exp 2+delta) . Here, kappa is the minimal Johnson Lindenstrauss dimension and delta is arbitrarily small. The projection succeeds, with probability 1-1/n, in preserving vector lengths, up to distortion epsilon, for all vectors such that || chi || infinity < || chi ||(sub 2)kappa(exp -1/2)d(exp -delta) (for arbitrary small delta). Sampling based approaches are either not applicable in linear time or require a bound on || chi || infinity that is strongly dependant on d. Our method overcomes these shortcomings by rapidly applying dense tensor power matrices to incoming vectors.

Limitations: APPROVED FOR PUBLIC RELEASE
Pages: 10
Report Date: DEC 2007
Report Number: A556874
Keywords relating to this report:
*VECTOR ANALYSIS
*WALSH TRANSFORMATION
LENGTH
SAMPLING
TIME
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