Swizzling (computer graphics)

In computer graphics, swizzling means rearranging the elements of a vector[1]. For example, if A = {1,2,3,4}, you could swizzle A to get B = A.wwxy, then B would equal {4,4,1,2}. This is common in GPGPU applications.

In terms of linear algebra, this is equivalent to multiplying by a matrix of zeros and ones such that each row has exactly one one. If $A=(1,2,3,4)^{T}$, then swizzling $A$ as above looks like

$A.wwxy={\begin{bmatrix}0&0&0&1\\0&0&0&1\\1&0&0&0\\0&1&0&0\end{bmatrix}}{\begin{bmatrix}1\\2\\3\\4\end{bmatrix}}={\begin{bmatrix}4\\4\\1\\2\end{bmatrix}}$.