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  2. Block swap algorithms - Wikipedia

    en.wikipedia.org/wiki/Block_swap_algorithms

    A rotation is an in-place reversal of array elements. This method swaps two elements of an array from outside in within a range. The rotation works for an even or odd number of array elements. The reversal algorithm uses three in-place rotations to accomplish an in-place block swap: Rotate region A; Rotate region B; Rotate region AB

  3. Rotation matrix - Wikipedia

    en.wikipedia.org/wiki/Rotation_matrix

    A 180° rotation (middle) followed by a positive 90° rotation (left) is equivalent to a single negative 90° (positive 270°) rotation (right). Each of these figures depicts the result of a rotation relative to an upright starting position (bottom left) and includes the matrix representation of the permutation applied by the rotation (center ...

  4. Estimation of signal parameters via rotational invariance ...

    en.wikipedia.org/wiki/Estimation_of_signal...

    Maximum overlapping of two sub-arrays (N denotes number of sensors in the array, m is the number of sensors in each sub-array, and and are selection matrices) The weight vector a ( ω k ) {\textstyle \mathbf {a} (\omega _{k})} has the property that adjacent entries are related.

  5. Rodrigues' rotation formula - Wikipedia

    en.wikipedia.org/wiki/Rodrigues'_rotation_formula

    Let k be a unit vector defining a rotation axis, and let v be any vector to rotate about k by angle θ (right hand rule, anticlockwise in the figure), producing the rotated vector . Using the dot and cross products , the vector v can be decomposed into components parallel and perpendicular to the axis k ,

  6. Kabsch algorithm - Wikipedia

    en.wikipedia.org/wiki/Kabsch_algorithm

    Let P and Q be two sets, each containing N points in .We want to find the transformation from Q to P.For simplicity, we will consider the three-dimensional case (=).The sets P and Q can each be represented by N × 3 matrices with the first row containing the coordinates of the first point, the second row containing the coordinates of the second point, and so on, as shown in this matrix:

  7. Quaternions and spatial rotation - Wikipedia

    en.wikipedia.org/wiki/Quaternions_and_spatial...

    The normalized rotation axis, removing the ⁡ from the expanded product, leaves the vector which is the rotation axis, times some constant. Care should be taken normalizing the axis vector when γ {\displaystyle \gamma } is 0 {\displaystyle 0} or k 2 π {\displaystyle k2\pi } where the vector is near 0 {\displaystyle 0} ; which is identity, or ...

  8. Cross-validation (statistics) - Wikipedia

    en.wikipedia.org/wiki/Cross-validation_(statistics)

    Of the k subsamples, a single subsample is retained as the validation data for testing the model, and the remaining k − 1 subsamples are used as training data. The cross-validation process is then repeated k times, with each of the k subsamples used exactly once as the validation data.

  9. Cayley transform - Wikipedia

    en.wikipedia.org/wiki/Cayley_transform

    where K = w 2 + x 2 + y 2 + z 2, and where w = 1. This we recognize as the rotation matrix corresponding to quaternion + + + (by a formula Cayley had published the year before), except scaled so that w = 1 instead of the usual scaling so that w 2 + x 2 + y 2 + z 2 = 1.