Communative Matrix Multiplcation

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of Doran, Harold
Sent: Tuesday, August 14, 2012 10:27 AM
To: Doran, Harold; 'r-help at r-project.org'
Subject: Re: [R] Communative Matrix Multiplcation

Meant to also add

library(Matrix)

for reproducing

From: Doran, Harold
Sent: Tuesday, August 14, 2012 1:26 PM
To: r-help at r-project.org
Subject: Communative Matrix Multiplcation

Friends

I'm not seeing why the following occurs:

T1 <- (A1 - A2) %*% D
T2 <- (A1 %*% D) - (A2 %*% D)
identical(T1, T2)

[1] FALSE

Harold

dput(A1)

new("dsCMatrix"
    , i = c(0L, 1L, 2L, 3L, 0L, 1L, 4L, 2L, 3L, 5L)
    , p = c(0L, 1L, 2L, 3L, 4L, 7L, 10L)
    , Dim = c(6L, 6L)
    , Dimnames = list(NULL, NULL)
    , x = c(5, 5, 5, 5, 5, 5, 10, 5, 5, 10)
    , uplo = "U"
    , factors = list()
)

dput(A2)

new("dgeMatrix"
    , x = c(1.41313955042629, 1.23647532592053, 1.36413787785255,
0.986247245800629,
2.64961487634682, 2.35038512365318, 1.23647532592053, 1.55872699943971,
0.579347997632991, 1.62544967700677, 2.79520232536024,
2.20479767463976,
1.36413787785255, 0.579347997632991, 2.75106274522123,
0.305451379293231,
1.94348587548554, 3.05651412451446, 0.986247245800629,
1.62544967700677,
0.305451379293232, 2.08285169789937, 2.6116969228074, 2.3883030771926,
2.64961487634682, 2.79520232536024, 1.94348587548554, 2.6116969228074,
5.44481720170706, 4.55518279829294, 2.35038512365318, 2.20479767463976,
3.05651412451446, 2.3883030771926, 4.55518279829294, 5.44481720170706
)
    , Dim = c(6L, 6L)
    , Dimnames = list(NULL, NULL)
    , factors = list()
)

dput(D)

new("ddiMatrix"
    , diag = "N"
    , Dim = c(6L, 6L)
    , Dimnames = list(NULL, NULL)
    , x = c(5, 5, 5, 5, 10, 10)
)