Strange Matrix Multiplication Behaviour

tr <- rep(1:2, 3)
tr

ex1 <- as.data.frame(matrix(1:12, 2, 6))
ex1

tr * ex1[1,]

(tr * ex1)[1,]

From: Wayne Jones

Hi there fellow R-users, 

Im seeing some strange behaviour when I multiply a vector by a matrix

Here is my script: 

tr

        1         2         3         4         5         6 
0.2217903 0.1560525 0.1487908 0.1671354 0.1590643 0.1471667 

ex1

           a         b          c          d          e          f
1  0.2309579 -3.279045 -0.6694697 -1.1024404  0.2303928 -1.5527404
2 -0.2865357 -2.519789 -0.1138712 -0.3571832 -2.6727913 -0.3296945

is.vector(tr)

[1] TRUE

is.data.frame(ex1)

[1] TRUE

tr* ex1[1,]

           a          b           c          d          e          f
1 0.05122423 -0.5117031 -0.09961092 -0.1842569 0.03664727 -0.2285117

(tr* ex1)[1,]

           a          b          c          d          e          f
1 0.05122423 -0.4878917 -0.1064887 -0.2445106 0.03428033 -0.2469855


Notice that the output from tr * ex[1,] is different from 
(tr* ex1)[1,]
Especially element number 4. 

I would naturally expect both vectors to be equivalent. 


Can anyone shed any light on my predicament??

version

         _              
platform i386-pc-mingw32
arch     i386           
os       mingw32        
system   i386, mingw32  
status                  
major    1              
minor    9.1            
year     2004           
month    06             
day      21             
language R              



Regards

Wayne Jones






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