matrix
Create a symmetric matrix by specifying upper or lower triangle
Fri, 05/09/2008 - 07:12 — JeffThe input is specified as the row-wise lower triangle or column-wise upper triangle.
Non-conformable matrix multiplication
Thu, 09/27/2007 - 18:49 — JeffThis question hit the R-help mailing list:
"I'm having trouble using the 'apply' function to multiply some arrays. Let A be a 500x2 array and B a 500x3 array. I need a vector C which has 6 columns being the first three the result of A[,1] * B and the second three the result of A[,2] * B. What is the most efficient way to express that? I'm trying to use 'apply' with no success..."
