Hypotrochoids
Phi (/faÉŖ/;[1] uppercase Ī¦, lowercase Ļ or Ļ; Ancient Greek: ĻĪµįæ pheĆ® [pŹ°Ć©Ć®ĢÆ]; Modern Greek: ĻĪ¹ fi [fi]) is the twenty-first letter of the Greek alphabet.
In Archaic and Classical Greek (c. 9th to 4th century BC), it represented an aspirated voiceless bilabial plosive ([pŹ°]), which was the origin of its usual romanization as āØphā©.
During the later part of Classical Antiquity, in Koine Greek (c. 4th century BC to 4th century AD), its pronunciation shifted to a voiceless bilabial fricative ([Éø]), and by the Byzantine Greek period (c. 4th century AD to 15th century AD) it developed its modern pronunciation as a voiceless labiodental fricative ([f]). The romanization of the Modern Greek phoneme is therefore usually āØfā©.
It may be that phi originated as the letter qoppa (Ļ, Ļ),
and initially represented the sound /kŹ·Ź°/
before shifting to Classical Greek [pŹ°].
[2] In traditional Greek numerals, phi has a value of 500 (ĻŹ¹) or 500,000 (ĶµĻ). The Cyrillic letter Ef (Š¤, Ń) descends from phi.
Pure states of wave functions
[edit]
Solutions in quantum mechanics can be expressed as pure States. The solution states, called eigenstates, are labeled with quantum numbers.
For example, when dealing with the energy spectrum of the electron in a hydrogen atom, the relevant pure states are identified by the principal quantum number n,
the angular momentum quantum number ā,
the magnetic quantum number m,
and the spin z-component sz.
For another example, if the spin of an electron is measured in any direction, there are two possible results: up or down.
A pure state here is represented by a two-dimensional complex vector ,
with a length of one; that is, withwhere and are the absolute values of and .
The postulates of quantum mechanics state that pure states, at a given time t, correspond to vectors in a separable complex Hilbert space, while each measurable physical quantity (such as the energy or momentum of a particle) is associated with a mathematical operator called the observable. The operator serves as a linear function that acts on the states of the system. The eigenvalues of the operator correspond to the possible values of the observable. For example, it is possible to observe a particle with a momentum of 1 kgā m/s if and only if one of the eigenvalues of the momentum operator is 1 kgā m/s. The corresponding eigenvector (which physicists call an eigenstate) with eigenvalue 1 kgā m/s would be a quantum state with a definite, well-defined value of momentum of 1 kgā m/s, with no quantum uncertainty. If its momentum were measured, the result is guaranteed to be 1 kgā m/s.
In geometry, a hyperboloid of revolution,
sometimes called a circular hyperboloid,
is the surface generated by rotating a hyperbola around one of its principal axes.
A hyperboloid is the surface obtained from a hyperboloid of revolution by deforming it by means of directional scalings, or more generally, of an affine transformation.
A hyperboloid is a quadric surface, that is, a surface defined as the zero set of a polynomial of degree two in three variables. Among quadric surfaces, a hyperboloid is characterized by not being a cone or a cylinder, having a center of symmetry, and intersecting many planes into hyperbolas. A hyperboloid has three pairwise perpendicular axes of symmetry, and three pairwise perpendicular planes of symmetry.
Affine transformation

In Euclidean geometry, an affine transformation or affinity (from the Latin, affinis, "connected with") is a geometric transformation that preserves lines and parallelism, but not necessarily Euclidean distances and angles.
More generally, an affine transformation is an automorphism of an affine space (Euclidean spaces are specific affine spaces), that is, a function which maps an affine space onto itself while preserving both the dimension of any affine subspaces (meaning that it sends points to points, lines to lines, planes to planes, and so on) and the ratios of the lengths of parallel line segments. Consequently, sets of parallel affine subspaces remain parallel after an affine transformation. An affine transformation does not necessarily preserve angles between lines or distances between points, though it does preserve ratios of distances between points lying on a straight line.
If X is the point set of an affine space, then every affine transformation on X can be represented as the composition of a linear transformation on X and a translation of X. Unlike a purely linear transformation, an affine transformation need not preserve the origin of the affine space. Thus, every linear transformation is affine, but not every affine transformation is linear.
Examples of affine transformations include translation, scaling, homothety, similarity, reflection, rotation, hyperbolic rotation, shear mapping, and compositions of them in any combination and sequence.
Viewing an affine space as the complement of a hyperplane at infinity of a projective space, the affine transformations are the projective transformations of that projective space that leave the hyperplane at infinity invariant, restricted to the complement of that hyperplane.
Comments
Post a Comment
No Comment