[R] Communative Matrix Multiplcation

[Doran, Harold]

I just updated my R and this no longer occurs. But, below is the sessionInfo() showing details of when this doesn't occur, which I should have posted in the OP

> sessionInfo()
R version 2.12.2 (2011-02-25)
Platform: x86_64-pc-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252    LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                           LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] lme4_0.999375-38   Matrix_0.999375-46 lattice_0.19-13   

loaded via a namespace (and not attached):
[1] grid_2.12.2   nlme_3.1-98   stats4_2.12.2 tools_2.12.2

> -----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 1:26 PM
> To: r-help at r-project.org
> Subject: [R] 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)
> )
> 
> 	[[alternative HTML version deleted]]
> 
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