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Topic: Differential form

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In the News (Thu 20 Jun 19)

  Differential form - Definition, explanation
A differential form is a mathematical concept in the fields of multivariate calculus, differential topology and tensors.
In differential geometry, a differential form of degree k is a smooth section of the kth exterior power of the cotangent bundle of a manifold.
For example, the differential of a smooth function on a manifold (a 0-form) is a 1-form.
www.calsky.com /lexikon/en/txt/d/di/differential_form.php   (878 words)

  CSDC : Why Differential Forms? Functional Substitution and PullBack
Given a differential form in terms of the variables and their differentials (say x and dx) on the final state (target of the map), the differential form is well defined functionally in terms of the variables (say y and dy) on the initial state (domain of the map).
A differential form is a "scalar invariant or a density invariant" with respect to diffeomorphisms.
Construct a differential form on (meaning in terms of the variables of x, dx) the final state, and then by functional substitution and use of the Jacobian map construct the well defined functional form of the differential form on the initial state (in terms of y and dy).
www22.pair.com /csdc/ed3/ed3fre1.htm   (988 words)

 Differential geometry and topology - Gurupedia
Differential geometry is the study of geometry using calculus.
A vector field is a function from a manifold to the disjoint union of its tangent spaces (this union is itself a manifold known as the tangent bundle), such that at each point, the value is an element of the tangent space at that point.
A symplectic manifold is a differentiable manifold equipped with a symplectic form (that is, a
www.gurupedia.com /d/di/differential_geometry.htm   (938 words)

 Maxwell's Equations
These basic equations of electricity and magnetism can be used as a starting point for advanced courses, but are usually first encountered as unifying equations after the study of electrical and magnetic phenomena.
Integral form in the absence of magnetic or polarizable media:
Differential form in the absence of magnetic or polarizable media:
hyperphysics.phy-astr.gsu.edu /hbase/electric/maxeq.html   (116 words)

 Differential equation Summary
A stochastic differential equation (SDE) is a differential equation in which one or more of the terms is a stochastic process, thus resulting in a solution which is itself a stochastic process.
A differential algebraic equation (DAE) is a differential equation comprising differential and algebraic terms, given in implicit form.
The theory of differential equations is closely related to the theory of difference equations, in which the coordinates assume only discrete values, and the relationship involves values of the unknown function or functions and values at nearby coordinates.
www.bookrags.com /Differential_equation   (2081 words)

 Springer Online Reference Works   (Site not responding. Last check: )
Differentials of the first order are most often encountered; these are differential forms of dimension 1 that are linear with respect to the differential of each of the variables
is a harmonic differential on the Riemann surface.
Of fundamental importance in the theory of differentials on Riemann surfaces is the problem of the existence of a harmonic and analytic differential with given singularities on an arbitrary Riemann surface
eom.springer.de /D/d032240.htm   (981 words)

 Partial differential equation Summary
Partial differentiation involves a process by which the derivatives of a function containing multiple independent variables are found by considering all but the variable of interest as fixed during differentiation.
Partial differential equations are used to formulate and solve problems that involve unknown functions of several variables, such as the propagation of sound or heat, electrostatics, electrodynamics, fluid flow, elasticity, or more generally any process that is distributed in space, or distributed in space and time.
Although the issue of the existence and uniqueness of solutions of ordinary differential equations has a very satisfactory answer with the Picard-Lindelöf theorem, that is far from the case for partial differential equations.
www.bookrags.com /Partial_differential_equation   (3679 words)

 Differential Forms and the Generalized Stokes Theorem
Differential forms are important concepts in mathematics and have ready applications in physics, but their nature is not intuitive.
The first step is to assert that differential forms are related to vectors in a very subtle way.
Differential forms are the dual spaces to the spaces of vector fields over Euclidean spaces.
www.sjsu.edu /faculty/watkins/difforms.htm   (1932 words)

 5.2 Differential Form of the Equations
These other forms involve differential equations derived by manipulating the integral form or an approximation of it by taking limits as the time and distance intervals approach zero.
This and other similar forms of the equations are the most common forms in the hydraulic literature.
The final form of the equations to be presented here is obtained by transforming the Saint-Venant form so that derivatives taken in the proper directions, called characteristic directions, can be written as ordinary derivatives and not partial derivatives.
il.water.usgs.gov /proj/feq/feqdoc/chap5_3.html   (650 words)

 PlanetMath: differential form
In particular, a differential 0-form is the same thing as a function.
The exterior derivative is a first-order differential operator
This is version 24 of differential form, born on 2002-06-05, modified 2006-09-25.
planetmath.org /encyclopedia/DifferentialForms.html   (326 words)

 Springer Online Reference Works   (Site not responding. Last check: )
is called the curvature form of the connection.
The necessity of condition 2) was established in this form by E.
The equations for the components of the connection form are called the structure equations for the connection in
eom.springer.de /C/c025150.htm   (211 words)

 Theory: Form Factors
The form factor from a differential area to an object is proportional to the projection of the object onto the unit hemisphere, and then the projection from the unit hemisphere down onto the unit circle.
Send rays out into the world and the form factor to an object is the number of rays that hit the object divided by the number of rays shot.
The differential area to differential area term is used as the kernel for numeric integration.
www.cs.utah.edu /~bes/graphics/radiosity/course-node17.html   (770 words)

 Digital hearing aid using differential signal representations - Patent 6044162
Differential AND conversion schemes are well known to those of ordinary skill in the art and will not disclosed in detail herein to avoid obscuring the invention.
The use of digital pulse width to drive the output transducer 24 follows from the fact that in the present invention the differential signal representations of the acoustical input are the time derivative of the acoustical input amplitude, rather than the acoustical input amplitude itself.
According to another aspect of the present invention, it has been recognized for a specific class of signals, including sound, that the DSP may be non-linear and a differential representation of the sampled signal may be used and the additive property of the law of linear superposition may be applied to the system outputs.
www.freepatentsonline.com /6044162.html   (11418 words)

 Why Differential Forms? FS_PB
The importance of the Cartan concept resides with the fact that differential forms are well defined objects with respect to Functional Substitution and the PullBack (FS_PB for short) relative to C1 differentiable maps from an initial variety of variables to a final state or variety of variables.
The coefficients of differential forms are either anti-symmetric co-variant tensors, or tensor densities, the most useful of field structures used to describe physical systems.
Construct a differential form on (meaning in terms of the variables of) the final state, and then by functional substitution and use of the Jacobian map construct the well defined functional form of the tensor coefficients of the differential form on the initial state.
www.uh.edu /~rkiehn/ed3/ed3fre1.htm   (440 words)

 Differential form   (Site not responding. Last check: )
A differential form is a mathematical concept in the fields of multivariate calculus, Differential topology and tensors.
The modern notation for the Differential form, as well as the idea of the Differential forms as being the wedge products of exterior derivatives forming an exterior algebra, was introduced by Elie Cartan.
Differential forms of degree k are integrated over k dimensional chains.
differential-form.peernet.sk   (602 words)

 PRoblem with differential form of Maxwell's third equation?
The differential form simply says that the curl of E is equal to minus the time rate of change of B field.
No, the differential form doesn't fail, because BY DEFINITION, you have to calculate the curl (or the circular integral in the integral formula) in a time-fixed loop, that is, a curve which is time-independent wrt the coordinate frame in which you are expressing the E and B fields.
I also understand that the commonly used differential form of Maxwell's equation assumes that if there IS moving free charge the reference frame should be taken to be the free charge itself, and this is why Maxwell's equation in differential form "works", but it simply does not convey all possible imformation.
www.physicsforums.com /showthread.php?t=120518   (2798 words)

 Ordinary Differential Equations
The differential equations must be expressed in normal form; implicit differential equations are not allowed, and other terms on the left-hand side are not allowed.
The form of the estimation that is preferred depends mostly on the model and data.
The form of the error in the model is also an important factor in choosing the form of the estimation.
www.asu.edu /sas/sasdoc/sashtml/ets/chap14/sect42.htm   (1678 words)

 Relations Used to Reduce the Conservation Equations to Differential Form
This involves converting from the "integral form" over a control volume or control surface, to a "differential form" which deals with small changes from point to point.
One very useful form is where the viscous stresses are related to the rate of strain of the fluid, through a linear expression.This is valid for "Newtonian Fluids".
The resulting form of the momentum equation is called the Navier-Stokes equation.
www.adl.gatech.edu /classes/lowspdaero/lospd3/conseq_differential.html   (1123 words)

 Differential k-Form -- from Wolfram MathWorld
An important operation on differential forms, the exterior derivative, is used in the celebrated
The minimum number of terms necessary to write a form is sometimes called the rank of the form, usually in the case of a two-form.
The rank of a form can also mean the dimension of its form envelope, in which case the rank is an integer-valued function.
mathworld.wolfram.com /Differentialk-Form.html   (300 words)

 Calculus Tutorials and Problems
The chain rule of differentiation of functions in calculus is presented along with several examples.
Linear approximation is another example of how differentiation is used to approximate functions by linear ones close to a given point.
Differentiation is used to analyze the properties such as intervals of increase, decrease, local maximum, local minimum of quadratic functions.
www.analyzemath.com /calculus.html   (1507 words) Trapped on a surface
The parametric form of this differential constraint happens to be (13.22).
It may be difficult, however, to obtain a parametric form of the differential model.
It is even quite difficult to determine whether a differential model is completely integrable, which means that the configurations are trapped on a lower dimensional surface.
msl.cs.uiuc.edu /planning/node666.html   (474 words)

 Differential forms. Why?
I was reading lethe's thread on differential forms and suddenly it dawned on me that I had no idea what differential forms were for, or why the process was developed.
A 1 form is the gradient of a function.
And a 3 form is the divergence of a function.
www.physicsforums.com /showthread.php?t=7892   (3378 words)

 DIFFERENTIAL EQUATIONS AND OSCILLATIONS   (Site not responding. Last check: )
The differential nature of these physical laws in turn may be a reflection of our use of continuous variables like position and probability.
(The use of differential equations may also reflect traditionally-trained physicists viewing problems in differential forms) A differential equation can be transformed into an integral equation, but since integral equations are not how we usually learn physics, laws are hardly ever stated originally as integral equations.
More specifically the the physical problem is: a non relativistic particle with mass m moves in one dimension under the influence of a conservative force F in an inertial frame of reference.
www.krellinst.org /UCES/archive/modules/diffeq   (263 words)

 [No title]
3) Evaluate the constant differential form 4dxdy+dydz on the squares determined by the standard basis in R3 (I,j,k).
Types of problems: 1) Determine the rank of a map; solve an equation y=f(x); 2) Compute the pullback of a k-form 3) Compute the differential of a k-form; 4) Integrate a k-form (parametrize -> pullback-> iterated integral) 5) Use Stokes Th.
differential forms & vector fields/scalar functions - Correspondence: differential forms and vector fileds/functions, exterior differentiation and differential operators (grad, curl, div) - Stokes Theorem (diff.
www.ilstu.edu /~lmiones/345rvs04.doc   (1028 words)

 ..Example 1..   (Site not responding. Last check: )
Is Separable - Because in differential form: 1dy + (2x-10) dx = 0 the coefficients (1) and (2x-10) are fns of one var.
Note that in expanded form, every occurrence of x or dx in a term is a single linear factor.
Step 1: Put the DE into the special Linear Form by creating the derivative dx/dy, and putting all terms with dx/dy and x on one side.
www.eduscape2000.com /DiffEq/expl1.html   (891 words)

 S.O.S. Mathematics CyberBoard :: View topic - Uniform Spherical Shell
The differential form for the surface is given by 1/n {dot} k, where n is a unit outward normal vector, and k is the unit vector in the k direction (since k is perpendicular to the projection plane of choice--in this case, the xy-plane).
However, this two form is equal to 1/(n dot k) dx^dy over the interior of the circle in the xy-plane, and the integral over this region is much easier to evaluate.
is equal to the integral of the form I gave over the interior of the circle, which is the projection of the sphere onto the xy-plane.
www.sosmath.com /CBB/viewtopic.php?p=114920   (677 words)

= sin x + C because (cos x) dx = d(sin x) and the differential of the constant C is zero.
By " friendly form " we mean that we know a formula for that form in terms of formulas for elementary functions.
In the example above, let u = v and dv = sin x dx and notice that v and du are known because u is differentiable and dv is integrable in " closed form ".
academ.hvcc.edu /~murrajoh/closedformintegration1.htm   (238 words)

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