# symmetric.pascal.matrix: Symmetric Pascal matrix In matrixcalc: Collection of functions for matrix calculations

## Description

This function returns an n by n symmetric Pascal matrix.

## Usage

 1 symmetric.pascal.matrix(n) 

## Arguments

 n Order of the matrix

## Details

In mathematics, particularly matrix theory and combinatorics, the symmetric Pascal matrix is a square matrix from which you can derive binomial coefficients. The matrix is an order n symmetric matrix with typical element given by {S_{i,j}} = {{n!} \mathord{≤ft/ {\vphantom {{n!} {≤ft[ {r!\;≤ft( {n - r} \right)!} \right]}}} \right. \kern-νlldelimiterspace} {≤ft[ {r!\;≤ft( {n - r} \right)!} \right]}} where n = i + j - 2 and r = i - 1. The binomial coefficients are elegantly recovered from the symmetric Pascal matrix by performing an LU decomposition as {\bf{S}} = {\bf{L}}\;{\bf{U}}.

## Value

An order n matrix.

## Note

If the argument n is not a positive integer, the function presents an error message and stops.

## Author(s)

Frederick Novomestky fnovomes@poly.edu

## References

Call, G. S. and D. J. Velleman, (1993). Pascal's matrices, American Mathematical Monthly, April 1993, 100, 372-376.

Edelman, A. and G. Strang, (2004). Pascal Matrices, American Mathematical Monthly, 111(3), 361-385.

## Examples

 1 2 S <- symmetric.pascal.matrix( 4 ) print( S ) 

matrixcalc documentation built on May 2, 2019, 1:45 p.m.