Brahmagupta matrix

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In mathematics, the following matrix was given by Indian mathematician Brahmagupta:[1]

B(x,y) = \begin{bmatrix}
x & y \\
\pm ty & \pm x \end{bmatrix}.

It satisfies

B(x_1,y_1) B(x_2,y_2) = B(x_1 x_2 \pm ty_1 y_2,x_1 y_2 \pm y_1 x_2).\,

Powers of the matrix are defined by

B^n = \begin{bmatrix}
x & y \\
ty & x \end{bmatrix}^n = \begin{bmatrix}
x_n & y_n \\
ty_n & x_n \end{bmatrix} \equiv B_n.

The \ x_n and \ y_n are called Brahmagupta polynomials. The Brahmagupta matrices can be extended to negative integers:

B^{-n} = \begin{bmatrix}
x & y \\
ty & x \end{bmatrix}^{-n} = \begin{bmatrix}
x_{-n} & y_{-n} \\
ty_{-n} & x_{-n} \end{bmatrix} \equiv B_{-n}.

See also[edit]

References[edit]

  1. ^ "The Brahmagupta polynomials". Suryanarayanan. The Fibonacci Quarterly. Retrieved 3 November 2011. 

External links[edit]