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Topic: Signum function

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	NationMaster - Encyclopedia: Signum function
		The signum function is the derivative of the absolute value function (up to the indeterminacy at zero):
		To avoid confusion with the sine function, this function is often called the signum function.
		The signum function is differentiable with derivative 0 everywhere except at 0.
	www.nationmaster.com /encyclopedia/Signum-function (276 words)

	Sign function - Wikipedia, the free encyclopedia
		In mathematics and especially in computer science, the sign function is a logical function which extracts the sign of a real number.
		To avoid confusion with the sine function, this function is often called the signum function.
		The signum function is differentiable with derivative 0 everywhere except at 0.
	en.wikipedia.org /wiki/Sign_function (196 words)

	PlanetMath: signum function
		In applications, such as the Laplace transform, this definition is adequate since the value of a function at a single point does not change the analysis.
		, the signum function is defined as [2]
		This is version 5 of signum function, born on 2003-05-05, modified 2007-05-09.
	www.planetmath.org /encyclopedia/HeavysideStepFunction.html (208 words)

	GNU Scientific Library -- Reference Manual - Linear Algebra
		This function unpacks the diagonal and subdiagonal of the encoded symmetric tridiagonal decomposition (
		This function unpacks the diagonal and subdiagonal of the encoded tridiagonal decomposition (
		This function unpacks the diagonal and superdiagonal of the bidiagonal decomposition of
	www.math.uni-bremen.de /techdoc/software/GSL/gsl-ref_12.html (2667 words)

	Heaviside step function - Wikipedia, the free encyclopedia
		The function is used in the mathematics of control theory and signal processing to represent a signal that switches on at a specified time and stays switched on indefinitely.
		It is the cumulative distribution function of a random variable which is almost surely 0.
		The Heaviside function is the integral of the Dirac delta function.
	en.wikipedia.org /wiki/Heaviside_step_function (203 words)

	CLHS: Function SIGNUM
		signum determines a numerical value that indicates whether number is negative, zero, or positive.
		For rational arguments, signum is a rational function, but it may be irrational for complex arguments.
		(signum 0) => 0 (signum 99) => 1 (signum 4/5) => 1 (signum -99/100) => -1 (signum 0.0) => 0.0 (signum #c(0 33)) => #C(0.0 1.0) (signum #c(7.5 10.0)) => #C(0.6 0.8) (signum #c(0.0 -14.7)) => #C(0.0 -1.0) (eql (signum -0.0) -0.0) => true
	www.lispworks.com /documentation/HyperSpec/Body/f_signum.htm (195 words)

	Sign function - Term Explanation on IndexSuche.Com (Site not responding. Last check: 2007-10-30)
		The signum function is the derivative of the absolute value function (up to the indeterminacy at zero): : {d \left
		Also, the derivative of the signum function is two times the Dirac_delta_function, : {d \ \hbox{sgn} \, x \over dx} = 2 \delta (x).
		The signum function is related to the Heaviside_step_function ''h0.5(x)'' thus : \hbox{sgn} \ x = 2 h_{0.5}(x) - 1, where the 0.5 subscript of the step function means that h_{0.5}(0) = 0.5.
	www.indexsuche.com /Sign_function.html (256 words)

	Dyalog APL (Site not responding. Last check: 2007-10-30)
		Signum Difference ----------------- The signum function (×) naturally partitions a line into three disjoint subsets, by producing three results (-1, 0, 1).
		We can apply signum to the difference between a value and the boundary point to produce the signum difference, which asks a more specific question, i.e.
		If we take the signum product of the x-coordinate with respect to the row coord- inates and the signum product of the y-coordinate with respect to the column co- ordinates, we obtain a ordered pair indicating the position in each direction.
	www.dyalog.com /dfnsdws/n_abc.htm (1233 words)

	PlanetMath: signum function
		A related function is the Heaviside step function defined as
		See Also: modulus of complex number, Heaviside step function
		Cross-references: complex conjugate, arguments, complex, unit circle, onto, projection, complex number, equation, calculate, almost everywhere, piecewise, real numbers, clear, Heaviside step function, extended real numbers, relations, Laplace transform, point, properties, function
	planetmath.org /encyclopedia/SignumFunction.html (208 words)

	Chapter 1
		The essence of a piecewise continuous function is that its definition breaks up the domain into separate pieces, for each of which a different algebraic or transcendental expression is valid.
		Piecewise continuous functions are not at all abstract, and as you get into the details of this chapter, you will come to realize that you have already been using many of them conceptually.
		The Heaviside step and the rectangle function are useful for chopping off a desired portion of a continuous function and eliminating the rest of it.
	www.csulb.edu /~rdayers/Courses/Chapter_1/chapter_1.htm (4855 words)

	CLHS: Function SIGNUM
		signum determines a numerical value that indicates whether number is negative, zero, or positive.
		For rational arguments, signum is a rational function, but it may be irrational for complex arguments.
		(signum 0) => 0 (signum 99) => 1 (signum 4/5) => 1 (signum -99/100) => -1 (signum 0.0) => 0.0 (signum #c(0 33)) => #C(0.0 1.0) (signum #c(7.5 10.0)) => #C(0.6 0.8) (signum #c(0.0 -14.7)) => #C(0.0 -1.0) (eql (signum -0.0) -0.0) => true
	www.cs.rit.edu /~swm/lisp/HyperSpec/Body/f_signum.htm (195 words)

	A Math Library (Site not responding. Last check: 2007-10-30)
		The signum function returns 1 if a value is positive, 0 if a value is 0, and -1 if a value is negative.
		The sine and cosine functions are integer-based approximations.
		The sine function exploits the fact that sine values are identical to cosine values with a 90 degree phase shift.
	www.acroname.com /brainstem/examples/math/math.html (646 words)

	[No title]
		The prototype for the `sigprocmask' function is in `signal.h'.
		When a handler function is invoked on a signal, that signal is automatically blocked (in addition to any other signals that are already in the process's signal mask) during the time the handler is running.
		Besides having different names for all the functions to avoid conflicts, the main differences between the two are: * BSD Unix represents signal masks as an `int' bit mask, rather than as a `sigset_t' object.
	osiris.sunderland.ac.uk /~cs0pdu/pub/info/libc.info-21 (6791 words)

	Aldor Compiler User Guide: Section IV, Chapter 21: First notes by T. Daly
		The function new should take the parts of a domain representation and construct a new instance of the domain from those parts.
		So, even if we have two functions with the same name, it is clear that the rest of the signature is different and so they are different.
		Local functions are in the implementation section of the code but their signature is not in the exports list.
	www.aldor.org /docs/HTML/chap21.html (7575 words)

	Math Forum - Ask Dr. Math Archives: High School Functions
		If a function can be manipulated so that it can't have a denominator equal to zero (and thus be undefined for that value), why is the original function still considered undefined at that value?
		The constant function f(x) = 0 will give zero no matter what function g(x) it is integrated with.
		The Math Forum is a research and educational enterprise of the Drexel School of Education.
	mathforum.org /library/drmath/sets/high_functions.html (740 words)

	GNU Scientific Library -- Reference Manual: LU Decomposition
		These functions compute the logarithm of the absolute value of the determinant of a matrix A, \lndet(A)
		This function may be useful if the direct computation of the determinant would overflow or underflow.
		These functions compute the sign or phase factor of the determinant of a matrix A, det(A)/det(A)
	linux.duke.edu /~mstenner/free-docs/gsl-ref-1.0/gsl-ref_203.html (400 words)

	[No title]
		double precision function signum(x) implicit none double precision x if (x.lt.0) then signum = -1 else if (x.eq.0) then signum = 0 else if (x.gt.0) then signum = 1 else * (must be that x is Not-a-Number) signum = x endif return end ======================================================================= double precision function func0(x) * test function for rootfinding routine.
		double precision function func0(x) implicit none double precision x func0 = (x-sqrt(2.0d0))sqrt(1+x2) return end ======================================================================= * double precision function func1(x) * test function for rootfinding routine.
		double precision function func1(x) implicit none double precision x func1 = (x-sqrt(2.0d0))*3 return end ======================================================================= * double precision function func2(x) * test function for rootfinding routine.
	www.math.nyu.edu /~braams/SciComp98/roots.f.1.html (409 words)

	datacraft solutions
		Managing signals to internal and external suppliers is a core function of what we do.
		Signum is designed as a stand-alone system, but it can also be implemented to provide a seamless interface to your existing system.
		Signum has reports available to the client and suppliers that enable them to monitor performance and demand.
	www.datacraftsolutions.com /signum_faq.shtml (442 words)

	dBforums - Sign function in C++
		Some languages have a function which returns the sign of an integer or double.
		The sign (or signum) function isn't actually very useful by itself so C and C++
		copysign() function that you have suggested is declared in , and hence alters
	www.dbforums.com /t350252.html (952 words)

	The Simulation Of Doppler Frequency Estimation Process for Reflected Location Signals
		The maximum value of the correlation function may be obtained when the frequency shift is equal to the Doppler frequency of reflected signal:
		The normalized magnitude of signum spectral correlation computed with (16) is shown in Figure 6.
		The major advantage of the signum spectral correlation lies in the simplicity of its physical implementation because it can transform complex multiplication into unit numbers addition.
	www.ici.ro /ici/revista/sic2001_1/art2.htm (872 words)

	SDL Delphi Component Suite - Signum (Site not responding. Last check: 2007-10-30)
		The function Signum evaluates the sign of the floating point number a and returns either +1 or -1.
		Please note that the function Signum differs from the function Sign of the Delphi unit Math in the way how a zero argument is treated: Signum returns +1 if a equals 0 (Sign returns 0).
		The term "Signum (-3.3)" returns the value -1.
	www.lohninger.com /helpcsuite/sign.htm (61 words)

	Info Node: (libc.info)Signal Sets
		Don't try to set all the signals explicitly because the `sigset_t' object might include some other information (like a version field) that needs to be initialized as well.
		The following `errno' error condition is defined for this function: `EINVAL' The SIGNUM argument doesn't specify a valid signal.
		Finally, there is a function to test what signals are in a signal set: -- Function: int sigismember (const sigset_t SET, int SIGNUM) The `sigismember' function* tests whether the signal SIGNUM is a member of the signal set SET.
	darbujan.fzu.cz /cgi-bin/info2www?(libc)Signal+Sets (445 words)

	Digital Watermarking from Signum Technologies
		Users should be aware that the site may not display or function correctly if viewed in other browsers.
		Signum Technologies Limited reserves the right to modify or adapt descriptions, specifications, prices or any other information, that may be stated on this site, without prior notice.
		However, Signum Technologies Limited does not accept any responsibility for the content of those sites, the owners of which do not necessarily have any link, commercial or otherwise, with Signum Technologies Limited.
	www.signumtech.com /template1.asp?pageID=36 (384 words)

	GNU Scientific Library -- Reference Manual - LU Decomposition
		These functions compute the determinant of a matrix @math{A} from its @math{LU} decomposition,
		These functions compute the logarithm of the absolute value of the determinant of a matrix @math{A}, @math{\lndet(A)}, from its @math{LU} decomposition,
		These functions compute the sign or phase factor of the determinant of a matrix @math{A}, @math{det(A)/det(A)}, from its @math{LU} decomposition,
	www.math.utah.edu /software/gsl/gsl-ref_203.html (419 words)

	Math Forum - Ask Dr. Math (Site not responding. Last check: 2007-10-30)
		Date: 05/31/2000 at 15:34:02 From: David Little Subject: Signum (calculus) I am trying to find a simple definition of the signum function and any practical examples of its usage.
		Date: 05/31/2000 at 15:43:47 From: Doctor Schwa Subject: Re: Signum (calculus) The function signum(x) is -1 when x is negative, 0 when x is 0, and 1 when x is positive.
		It's also very handy for piecing together any functions with discontinuities.
	www.mathforum.com /library/drmath/view/53397.html (91 words)

	12.5.2. Trigonometric and Related Functions
		function therefore has a branch cut along the negative real axis.
		is a rational function, but it may be irrational for complex arguments.
		These functions compute the hyperbolic sine, cosine, tangent, arc sine, arc cosine, and arc tangent functions, which are mathematically defined for an argument z as follows:
	cltl2.lisp.se /cltl/clm/node128.html (1253 words)

	Sign function (Site not responding. Last check: 2007-10-30)
		Also, the derivative of the signum function is two times the Dirac delta function,
		where the 0.5 subscript of the step function means that
		(x) = 0, then the signum function can be expressed as
	www.mcfly.org /wik/Sign_function (170 words)

	StrictMath (Java 2 Platform SE 5.0)
		To help ensure portability of Java programs, the definitions of some of the numeric functions in this package require that they produce the same results as certain published algorithms.
		Returns the signum function of the argument; zero if the argument is zero, 1.0 if the argument is greater than zero, -1.0 if the argument is less than zero.
		Returns the signum function of the argument; zero if the argument is zero, 1.0f if the argument is greater than zero, -1.0f if the argument is less than zero.
	java.sun.com /j2se/1.5.0/docs/api/java/lang/StrictMath.html (3979 words)

	Index
		This index includes links for most Common Lisp functions (and other entities) to the portion of the online Common Lisp manual where they are defined.
		Also, the links do not jump directly to the function definitions; instead, they connect to the beginning of the sections where they are defined.
		Finally, please note that it is sometimes useful to go the previous section or the beginning of the chapter to get an introductory explanation (maybe even a simple example) of what is going on.
	cltl2.lisp.se /cltl/clm (143 words)

	Math Forum Discussions
		> > > function, NOT the sin function.
		> > Of course, if one were to take the signum function to be
		> > But the signum function is most commonly defined so that sgn(0) = 0.
	www.mathforum.org /kb/message.jspa?messageID=517784&tstart=0 (330 words)

	GNU Scientific Library -- Reference Manual - LU Decomposition
		These functions solve the square system A x = b using the LU decomposition of A into (
		These functions solve the square system A x = b in-place using the LU decomposition of A into (
		It is preferable to avoid direct use of the inverse whenever possible, as the linear solver functions can obtain the same result more efficiently and reliably (consult any introductory textbook on numerical linear algebra for details).
	www.network-theory.co.uk /docs/gslref/gsl-ref_220.html (516 words)

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