From krys at maths.lth.se  Fri Jun  1 17:03:26 2007
From: krys at maths.lth.se (krys at maths.lth.se)
Date: Fri,  1 Jun 2007 17:03:26 +0200 (CEST)
Subject: [Rd] Determinant function (PR#9715)
Message-ID: <20070601150326.7AA6448CF1@slim.kubism.ku.dk>

Full_Name: Krzysztof Podgorski
Version: R version 2.4.1 (2006-12-18)
OS: Windows XP
Submission from: (NULL) (130.235.3.79)


The function ''det'' works improperly for a singular matrix and returns a
non-zero value even if ''solve'' reports singularity. The matrix is very simple
as shown below.

A <- diag(rep(c(64,8), c(8,8)))
A[9:16,1] <- 8
A[1,9:16] <- 8

det(A)
#[1] -196608
solve(A)
#Error in solve.default(A) : system is computationally singular: reciprocal
condition number = 2.31296e-18



[Rd] Determinant function (PR#9715)
krys at maths.lth.se