From alexis.sarda at gmail.com  Fri Sep 16 12:41:14 2016
From: alexis.sarda at gmail.com (Alexis Sarda)
Date: Fri, 16 Sep 2016 12:41:14 +0200
Subject: [Rd] Numerical accuracy of matrix multiplication
Message-ID: <CAA4naPDPXh2Q+KUMQhBJs4cecOC7uetbxihz_fxxk92JZNPLKg@mail.gmail.com>

Hello,

while testing the crossprod() function under Linux, I noticed the following:

set.seed(883)
x <- rnorm(100)
x %*% x - sum(x^2) # equal to 1.421085e-14

Is this difference normal? It seems to be rather large for double precision.

Regards,
Alexis.

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[Rd] Numerical accuracy of matrix multiplication
Alexis Sarda