In mathematics, Krawtchouk matrices are matrices whose entries are values of Krawtchouk polynomials at nonnegative integer points. The Krawtchouk matrix K(N) is an (N+1)×(N+1) matrix. Here are the first few examples:
K(0)=[1]K(1)=[111−1]K(2)=[11120−21−11]K(3)=[111131−1−33−1−131−11−1]{\displaystyle K^{(0)}={\begin{bmatrix}1\end{bmatrix}}\qquad K^{(1)}=\left[{\begin{array}{rr}1&1\\1&-1\end{array}}\right]\qquad K^{(2)}=\left[{\begin{array}{rrr}1&1&1\\2&0&-2\\1&-1&1\end{array}}\right]\qquad K^{(3)}=\left[{\begin{array}{rrrr}1&1&1&1\\3&1&-1&-3\\3&-1&-1&3\\1&-1&1&-1\end{array}}\right]}K(4)=[11111420−2−460−2064−202−41−11−11]K(5)=[111111531−1−3−5102−2−221010−2−222−105−311−351−11−11−1].{\displaystyle K^{(4)}=\left[{\begin{array}{rrrrr}1&1&1&1&1\\4&2&0&-2&-4\\6&0&-2&0&6\\4&-2&0&2&-4\\1&-1&1&-1&1\end{array}}\right]\qquad K^{(5)}=\left[{\begin{array}{rrrrrr}1&1&1&1&1&1\\5&3&1&-1&-3&-5\\10&2&-2&-2&2&10\\10&-2&-2&2&2&-10\\5&-3&1&1&-3&5\\1&-1&1&-1&1&-1\end{array}}\right].}
![{\displaystyle K^{(0)}={\begin{bmatrix}1\end{bmatrix}}\qquad K^{(1)}=\left[{\begin{array}{rr}1&1\\1&-1\end{array}}\right]\qquad K^{(2)}=\left[{\begin{array}{rrr}1&1&1\\2&0&-2\\1&-1&1\end{array}}\right]\qquad K^{(3)}=\left[{\begin{array}{rrrr}1&1&1&1\\3&1&-1&-3\\3&-1&-1&3\\1&-1&1&-1\end{array}}\right]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/b11373862068ca4c8c558e6b941a8c38d137003f)
![{\displaystyle K^{(4)}=\left[{\begin{array}{rrrrr}1&1&1&1&1\\4&2&0&-2&-4\\6&0&-2&0&6\\4&-2&0&2&-4\\1&-1&1&-1&1\end{array}}\right]\qquad K^{(5)}=\left[{\begin{array}{rrrrrr}1&1&1&1&1&1\\5&3&1&-1&-3&-5\\10&2&-2&-2&2&10\\10&-2&-2&2&2&-10\\5&-3&1&1&-3&5\\1&-1&1&-1&1&-1\end{array}}\right].}](https://wikimedia.org/api/rest_v1/media/math/render/svg/3fe08d1f2b18ef9c0cfe249575de9c7fd6532df1)
