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Discrete - Wikipedia, the free encyclopedia In discrete mathematics and in theoretical computer science, the abstract world is usually modeled as a discrete space with discrete time. In discrete mathematics, without notion of continuity, a discrete set is a countable set; this concept is also important for combinatorics, probability theory, and statistical theory. In topology, a branch of mathematics, a discrete space is a topological space in which all sets are open, and a discrete set is a set of isolated points. en.wikipedia.org /wiki/Discrete   (275 words)

Discrete time - Wikipedia, the free encyclopedia Usage: when the phrase "discrete time" is used as a noun it should not by hyphenated; when it is a compound adjective, as when one writes of a "discrete-time stochastic process", then, at least according to traditional punctuation rules, it should be hyphenated. Uniformly sampled discrete time signals can be expressed as the time-domain multiplication between a pulse train and a continuous time signal. In contrast to continuous-time systems, where the behaviour of a system is often described by a set of linear differential equations, discrete-time systems are described in terms of difference equations. en.wikipedia.org /wiki/Discrete_time   (281 words)

Discrete mathematics - Encyclopedia.WorldSearch Discrete mathematics, sometimes called finite mathematics, is the study of mathematical structures that are fundamentally discrete, in the sense of not supporting or requiring the notion of continuity. Concepts and notations from discrete mathematics are useful to study or express objects or problems in computer algorithms and programming languages. Discrete mathematics has become popular in recent decades because of its applications to computer science. encyclopedia.worldsearch.com /discrete_mathematics.htm   (435 words)

Discrete time control apparatus - Patent 4791548 A discrete time control apparatus as recited in claim 5, wherein the means for distinguishing transient from normal operating conditions further comprises means for comparing a preset value and a value obtained from a measuring unit. A discrete time control apparatus as recited in claim 1, wherein the sampling/detecting means comprises means for adding the controlled system variable to a disturbance and a measuring unit. A discrete time control apparatus as recited in claim 5, further comprising means for selecting the binary mode under transient conditions and the continuous mode under normal operating conditions. www.freepatentsonline.com /4791548.html   (3709 words)

Stata Library: Discrete Time Survival Analysis Discrete time survival analysis treats time not as a continuous variable, but as being divided into discrete units or chunks. In order to do discrete time survival analysis we to have as many observations as there are time periods for each patient. We will be able to analyze discrete time data using logistic regression with indicator variables for each of the time periods. www.ats.ucla.edu /stat/stata/Library/survival2.htm   (795 words)

DES Discrete event models which use continuous state and continuous time axis differ from continuous models by the fact that only a finite number of state changes may occur within finite time interval depending on instantaneous "events". Continuous models are represented through sets of differential equations, and discrete time models through sets of difference equations. The discrete event system is driven by events, and a typical example of discrete system is a queueing system shown as Figure 2. www.acims.arizona.edu /SOFTWARE/devscpp/v41_2.htm   (391 words)

Simulink and the DSP Blockset (DSP Blockset) The time instants where the signal is defined are called the signal's sample times; traditionally, a discrete signal is considered to be undefined at points in time between these instants. Because in these modes a discrete-time signal is defined between sample times, if you sample the signal with a rate or phase that is distinct from the signal's own rate and phase, you still measure meaningful values. Simulink offers the ability to shift a signal's sample times by an arbitrary value, which is equivalent to shifting the signal's phase by a fractional sample period. www.tau.ac.il /cc/pages/docs/matlab/help/toolbox/dspblks/dspi12.html   (969 words)

Discrete Time Discrete time models are used when something behaves in a periodical fashion. In the case of 17 and 13 year periodical cicadas, we would think of their populations changing in time steps 17 and 13 years long. t = 0 (time zero), that is, when we first start observing the cicadas. www.andrews.edu /~chantel/research/mymodel/time.htm   (364 words)

Computing Papers on Discrete Discrete time models are frequently applied to digital systems where the clock defines the required Discrete steps. Discrete math is used, for example, whenever objects are counted, when relationships between finite sets are studied, and when processes involving a finite number of steps are analyzed. Both Discrete math courses should be required the first year, just as engineering programs require two semesters of calculus in year one. computing.breinestorm.net /Discrete   (2739 words)

Is Space-Time Discrete? However, such observations and the discovery of quantum theory with its discrete energy levels and the Heisenberg uncertainty principle led physicists to speculate that space-time itself may be discrete as early as the 1930's. After matter and light, history is repeating itself for a third time and now it is space-time which is threatened to be reduced to discrete events. It has been apparent since early times that there is something different between the mathematical properties of the real numbers and the quantities of measurement in physics at small scales. www.karlin.mff.cuni.cz /~motl/Gibbs/discrete.htm   (2783 words)

Continuous-time to discrete-time system con- version ing to discrete time, the overall effect of the constant is canceled. model can be expressed as a signal flowchart in discrete time. introduce 1/T when going from discrete to continuous time, and T when return- www.faqs.org /docs/sp/sp-20.html   (380 words)

Discrete PID Controllers The position of the poles and zeros of the discrete transfer functions depend on the sampling interval used. Although this characteristic is not of great significance in PID type algorithms, it becomes important when discrete process models are used directly in the design of digital controllers. From experience, a sampling interval of approximately 10% of the dominant time constant works well in practise. lorien.ncl.ac.uk /ming/digicont/digimath/dpid1.htm   (1030 words)

Discrete-Time Systems The time invariance is defined by considering an input sequence x(n), which over time or that produce an output sequence at a rate different from that of If the system is time invariant, the response to x(n - D) is equal to www.faqs.org /docs/sp/sp-17.html   (301 words)

Discrete Time Mechanics In those recent papers there is a discussion of time as a quantum process and an explanation of why it is necessarily discrete. What I did for a number of years was to investigate the hypothesis that time should be modelled by an ordered discrete set such as the integers, rather than a continuum. Time is one of the great enigmas of existence which has been discussed and speculated upon since antiquity. www.maths.nottingham.ac.uk /personal/gaj/discrete.html   (740 words)

Essays in discrete time asset pricing I define a discrete time affine process as one where the conditional cumulant generating function is affine in the current state. Most discrete time literature uses the beta that results from a regression of an asset's simple returns on various factors to quantify risk. Flow of information is modeled as the discreteness τ in a discrete-time economy. repository.upenn.edu /dissertations/AAI3031711   (356 words)

kalman.html After each time and measurement update pair, the process is repeated with the previous a posteriori estimates used to project or predict the new a priori estimates. The time update equations are responsible for projecting forward (in time) the current state and error covariance estimates to obtain the a priori estimates for the next time step. The time update equations can also be thought of as predictor equations, while the measurement update equations can be thought of as corrector equations. www.cs.brown.edu /stc/education/course95-96/Kalman-Filters/kalman.html   (3083 words)

Sampling and Discrete Time Fourier Transform Because the sampled signal is discrete in time, it is convenient to refer to its spectrum as the Discrete Time Fourier Transform (DTFT). One of the characteristic of sampled signals is that they are discrete in the time domain. This discreteness gives rise to a periodic spectrum in the frequency domain with a period equal to the sampling frequency. dspcan.homestead.com /files/Sdtft/dtftintr.htm   (205 words)

BLOG@STEFANGEENS.COM But the fact that time may be discrete at a fundamental level — massive though this conceptual shift would be — is only half my point. That's my other half point, then: I quite simply find it remarkable that the mind "samples" its sensory inputs, and derives conscious states based on them, at discrete time intervals. This time, his patients had a problem with their visual perception, in that it sometimes slowed down enormously, so that they no longer perceived their surroundings continuously, but instead as a series of disjointed images, much like a flickering film or even a slideshow. www.stefangeens.com /000344.html   (1622 words)

ipedia.com: Binomial options model Article Similar assumptions underpin both the binomial model and the Black-Scholes model, and the binomial model thus provides a discrete time approximation to the continuous process underlying the Black-Scholes model. The model differs from other option pricing models, in that it uses a “discrete-time” model of the varying price over time of financial instruments; the model is thus able to handle a variety of conditions for which other models cannot be applied. The Binomial Value is found for each node, starting at the penultimate time step, and working back to the first node of the tree, the valuation date, where the calculated result is the value of the option. www.ipedia.com /binomial_options_model.html   (891 words)

Discrete-Time Integrator (Using Simulink) The Discrete-Time Integrator block can be used in place of the Integrator block when constructing a purely discrete system. T is the sampling period (delta T in the case of triggered sampling time). Although the values are the same, Simulink generates them at slightly different times, which protects your model from these problems. www.rdg.ac.uk /ITS/Topic/Graphics/GrGMatl601/Matlab6/toolbox/simulink/ug/discretetimeintegrator.html   (1167 words)

ee351_syllabus.html This course provides foundational education for students in sampling of continuous-time signals and in time, frequency, and Z-domain descriptions of discrete-time signals and systems. Introduction to discrete-time signal processing; sampling, linear time-invariant systems, discrete-time Fourier transform and discrete Fourier transform, Z transform. This course provides EE grounding in sampling, discrete-time signals, and discrete systems. www.ee.psu.edu /acadaff/courses/ee351_syllabus.html   (582 words)

Discrete time systems     time for the discrete approximation to the continuous system.     For discrete-time models, T should be of the form  Ti:Ts:Tf where Ts is the sample time.     returns the output and state time history in the matrices Y and X. No plot is drawn on the screen. www.coe.montana.edu /ee/jpeterson/Matlab_step_response_examples.htm   (346 words)

Discrete-Time System Analysis To perform discrete time convolution, x[n]*h[n], define the vectors x and h with elements in the sequences x[n] and h[n]. for discrete time are used exactly the same way as for the continuous time case discussed in Section 3.F. Most of the commands for the continuous time state space representation also work for the discrete time state space. users.ece.gatech.edu /~bonnie/book/TUTORIAL/tut_4.html   (1347 words)

EconPapers: Discrete time hedging errors for options with irregular payoffs As regards the perfect continuous hedging, this discrete time strategy induces, for the trader, a risk which we analyze w.r.t. Abstract: In a complete market with a constant interest rate and a risky asset, which is a linear diffusion process, we are interested in the discrete time hedging of a European vanilla option with payoff function f. Keywords: Discrete time hedging; approximation of stochastic integral; rate of convergence. econpapers.repec.org /article/sprfinsto/v_3A5_3Ay_3A2001_3Ai_3A3_3Ap_3A357-367.htm   (274 words)

ECE 4660: Lab 4-Discrete-time modulation and demodulation Then the filters will "inherit" their sample times from the previous block. When available, set the "Sample Time" in the filter blocks to -1. Otherwise, you must set the sample times explicitly. www.engineering.usu.edu /classes/ece/4660/lab4/lab4.html   (857 words)

Part 2: Discrete Time Convolution If a discrete time signal of length L is convolved with a discrete signal of length M, what will be the length of the resulting signal? Is the waveform which results from the discrete-time convolution the same as (or similar to) what would be obtained by sampling the result of the continuous-time convolution of the analog signals. Use these sampled signals to perform a discrete time convolution. www.eas.asu.edu /~eee407/labf00/node4.html   (324 words)

Convolution - Discrete time Letting ℋ be a discrete time LTI system, we start with the folowing equation and work our way down the the convoluation sum. Johns Hopkins University has an excellent Discrete time convolution applet. See that at time 1, we are multiplying two elements of the input signal by two elements of the impulse respone. cnx.rice.edu /content/m11539/latest   (839 words)

Discrete Time and Quantum Cosmology My researches on Discrete Time have now entered the phase where questions on cosmology can be considered. We simply suppose that the entire universe is described by such a (time dependent) state. Most of the time, people forget about such questions, and so ignore a fundamental puzzle in quantum theory. www.maths.nott.ac.uk /personal/jag/future.html   (1300 words)

Discrete time signals Generally a time discrete signal is a sequence of real or complex numbers. The unit sample function is very useful in that it can be seen as the elementary constituent in any discrete signal. The discrete trigonometric functions are defined as follows. cnx.rice.edu /content/m11476/latest   (400 words)

6.341 Discrete-Time Signal Processing - Home Representation, analysis, and design of discrete time signals and systems. Time-and frequency-domain design techniques for recursive (IIR) and non-recursive (FIR) filters. web.mit.edu /6.341/Fall05/www   (242 words)

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