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Let each curve C t in the family be given as the solution of an equation f t (x, y)=0 (see implicit curve), where t is a parameter. Write F(t, x, y)=f t (x, y) and assume F is differentiable. The envelope of the family C t is then defined as the set of points (x,y) for which, simultaneously,
The envelope thus generalizes the concept of a constant amplitude into an instantaneous amplitude. The figure illustrates a modulated sine wave varying between an upper envelope and a lower envelope. The envelope function may be a function of time, space, angle, or indeed of any variable. Envelope for a modulated sine wave.
The upper envelope or pointwise maximum is defined symmetrically. For an infinite set of functions, the same notions may be defined using the infimum in place of the minimum, and the supremum in place of the maximum. [1] For continuous functions from a given class, the lower or upper envelope is a piecewise function whose pieces are from the ...
In mathematics, the lower convex envelope ˘ of a function defined on an interval [,] is defined at each point of the interval as the supremum of all ...
By Hopf–Lax formula, the Moreau envelope is a viscosity solution to a Hamilton–Jacobi equation. [3] Stanley Osher and co-authors used this property and Cole–Hopf transformation to derive an algorithm to compute approximations to the proximal operator of a function. [4]
R(t) is called the envelope of the signal. Hence an AM signal is given by the function = (+ ()) with m(t) representing the original audio frequency message, C the carrier amplitude and R(t) equal to C + m(t). So, if the envelope of the AM signal can be extracted, the original message can be recovered.
Write the return address in the top left corner. Write the recipient's address slightly centered on the bottom half of the envelope. Place the stamp in the top right corner.
The evolute of a curve (in this case, an ellipse) is the envelope of its normals. In the differential geometry of curves, the evolute of a curve is the locus of all its centers of curvature. That is to say that when the center of curvature of each point on a curve is drawn, the resultant shape will be the evolute of that curve.