Matrix multiplication

[Riyanto Wibowo <riyantowibowo@yahoo.com.sg>]

Dear All,

I want to perform matrix multiplication for large size of matrix. I could perform it with this function, unfortunately it takes almost 25 seconds.

 

function()
{

 a <- matrix(runif(100000), 50000, 2)
 P <- numeric(50000)
 b <- matrix(0, 2, 1)
 b[1, 1] <- 10
 b[2, 1] <- 20
 for(i in 1:50000) {
  P[i] <- a[i, 1:2] %*% b
 }
}

 

Could anyone help me how to perform matrix multiplication with the most efficient/fastest way? Is it possible ?

 

Thank you very much.

 

Regards,

 

Ryan

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