Energy efficiency is a key concern in the design of modern computer systems. One promising approach to energyefficient computation, approximate computing, trades off output precision for energy efficiency. However, this tradeoff can have unexpected effects on computation quality. This paper presents dynamic-analysis tools to debug and monitor the quality of approximate computations. We propose ...

Popular parametric models of speech sounds such as the sourcefilter model provide a fixed means of describing the variability inherent in speech waveform data. However, nonlinear dimensionality reduction techniques such as the intrinsic Fourier analysis method of Jansen and Niyogi provide a more flexible means of adaptively estimating such structure directly from data. Here we employ this appro...

A family of Root Mean Square Error of Approximation (RMSEA) statistics is proposed for assessing the goodness of approximation in discrete multivariate analysis with applications to item response theory (IRT) models. The family includes RMSEAs to assess the approximation up to any level of association of the discrete variables. Two members of this family are RMSEA2, which uses up to bivariate m...

We present analysis of an efficient algorithm for the approximate median selection problem that has been rediscovered many times, and easy to implement. The contribution of the article is in precise characterization of the accuracy of the algorithm. We present analytical results of the performance of the algorithm, as well as experimental illustrations of its precision.∗

The present paper deals with the problem of calculating queue length distributions in a priority queueing model with a preemptive-resume policy under the assumption of general arrival and service distributions. The multi-queue priority system is decomposed into single-queue vacation systems, for which the visit and inter-visit distributions are approximated by the idle and busy period of a ΣGI/...

We solve for the availability of an n-processor VAXcluster system using a hierarchical approach that allows us to: 1) obtain a closed-form answer to an apparently difficult problem, and 2) determine the optimal number of processors in the cluster for a given set of cluster parameters. Our novel approach is a 2-level hierarchical model in which the lower-level model is a 9-state Markov chain tha...

The complexity of parallel applications and parallel processor scheduling policies makes both exact analysis and simulation diicult, if not intractable, for large systems. In this paper we propose a new approach to performance modeling of multiprogrammed processor scheduling policies, that of interpolation approximations. We rst deene a workload model that contains parameters for the essential ...

The paper deals with an enhanced method for matrix-based approximate symbolic analysis. The method assures the validity of approximated expressions over a certain interval of network parameters by means of the sensitivity analysis. A computationally effective algorithm is presented. Key-Words: Approximate symbolic analysis, linear circuits, computer methods

We analyze the performance of queues that serve readers and writers. Readers are served concurrently , while writers require exclusive service. We approximately analyze a rst-come-rst-serve (FCFS) reader/writer queue, and derive simple formulae for computing waiting times and capacity under the assumption of Poisson arrivals and exponential service. We extend the analysis to handle a one-writer...

Singular spectrum analysis (SSA) is a method of time-series analysis based on the singular value decomposition of an associated Hankel matrix. We present an approach to SSA using an effective and numerically stable high-degree polynomial approximation of a spectral projector, which also provides a means of time-series forecasting. Several numerical examples illustrating the algorithm are given.