title: Testing symmetry on symmetric matrix fails
body: <p>I have a symmetric matrix (4x4) in memory.  Unfortunately, sum( originalMatrix != t( originalMatrix ) ) = 6.  So I dput that matrix and read it back into memory.  Now sum( dputMatrix!= t( dputMatrix) ) = 0.  How is that possible and how can I test for symmetry with my in-memory matrix?</p>
  
  <pre><code>originalMatrix = ...
  sum( originalMatrix != t( originalMatrix ) )  # results in 6
  dput( originalMatrix )
  dputMatrix = structure(c(0.00117771346463494, -1.57864028664711e-05, 0.000293652924987303, 
  -9.85387333663002e-05, -1.57864028664711e-05, 0.000194782042576016, 
  6.9133672862693e-05, 4.23792732612071e-05, 0.000293652924987303, 
  6.9133672862693e-05, 0.00046216043028767, 2.70172523991749e-05, 
  -9.85387333663002e-05, 4.23792732612071e-05, 2.70172523991749e-05, 
  0.00017694896679169), .Dim = c(4L, 4L), .Dimnames = list(c("a00088630", 
  "a0091n", "a01010", "a01307810"), c("a00088630", "a0091n", "a01010", 
  "a01307810")))
  sum( dputMatrix != t( dputMatrix ) )  # results in 0!!!
  </code></pre>