[R] Speed up sum of outer products?

[AjayT]

Hey thanks alot guys !!! That really speeds things up !!! I didn't know %*%
and crossprod, could operate on matrices. I think you've saved me hours in
calculation time. Thanks again.

> system.time({C=matrix(0,50,50);for(i in 1:n)C = C + (X[i,] %o% X[i,])}) 
   user  system elapsed 
   0.45    0.00    0.90 
> system.time({C1 = t(X) %*% X}) 
   user  system elapsed 
   0.02    0.00    0.05 
> system.time({C2 = crossprod(X)})
   user  system elapsed 
   0.02    0.00    0.02 

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