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  2. Rotation of axes in two dimensions - Wikipedia

    en.wikipedia.org/wiki/Rotation_of_axes_in_two...

    In mathematics, a rotation of axes in two dimensions is a mapping from an xy-Cartesian coordinate system to an x′y′-Cartesian coordinate system in which the origin is kept fixed and the x′ and y′ axes are obtained by rotating the x and y axes counterclockwise through an angle .

  3. Rotation matrix - Wikipedia

    en.wikipedia.org/wiki/Rotation_matrix

    Thus we can write the trace itself as 2w 2 + 2w 21; and from the previous version of the matrix we see that the diagonal entries themselves have the same form: 2x 2 + 2w 21, 2y 2 + 2w 21, and 2z 2 + 2w 21. So we can easily compare the magnitudes of all four quaternion components using the matrix diagonal.

  4. 2D computer graphics - Wikipedia

    en.wikipedia.org/wiki/2D_computer_graphics

    Since a translation is an affine transformation but not a linear transformation, homogeneous coordinates are normally used to represent the translation operator by a matrix and thus to make it linear. Thus we write the 3-dimensional vector w = (w x, w y, w z) using 4 homogeneous coordinates as w = (w x, w y, w z, 1). [1]

  5. Transformation matrix - Wikipedia

    en.wikipedia.org/wiki/Transformation_matrix

    In linear algebra, linear transformations can be represented by matrices.If is a linear transformation mapping to and is a column vector with entries, then there exists an matrix , called the transformation matrix of , [1] such that: = Note that has rows and columns, whereas the transformation is from to .

  6. Scale-invariant feature transform - Wikipedia

    en.wikipedia.org/wiki/Scale-invariant_feature...

    where the model translation is [t x t y] T and the affine rotation, scale, and stretch are represented by the parameters m 1, m 2, m 3 and m 4. To solve for the transformation parameters the equation above can be rewritten to gather the unknowns into a column vector.

  7. Type conversion - Wikipedia

    en.wikipedia.org/wiki/Type_conversion

    In computer science, type conversion, [1] [2] type casting, [1] [3] type coercion, [3] and type juggling [4] [5] are different ways of changing an expression from one data type to another. An example would be the conversion of an integer value into a floating point value or its textual representation as a string, and vice versa.

  8. Fast Walsh–Hadamard transform - Wikipedia

    en.wikipedia.org/wiki/Fast_Walsh–Hadamard...

    Python example code [ edit ] import math def fwht ( a ) -> None : """In-place Fast Walsh–Hadamard Transform of array a.""" assert math . log2 ( len ( a )) . is_integer (), "length of a is a power of 2" h = 1 while h < len ( a ): # perform FWHT for i in range ( 0 , len ( a ), h * 2 ): for j in range ( i , i + h ): x = a [ j ] y = a [ j + h ] a ...

  9. Python syntax and semantics - Wikipedia

    en.wikipedia.org/wiki/Python_syntax_and_semantics

    A snippet of Python code with keywords highlighted in bold yellow font. The syntax of the Python programming language is the set of rules that defines how a Python program will be written and interpreted (by both the runtime system and by human readers). The Python language has many similarities to Perl, C, and Java. However, there are some ...