"I have two arrays A and B. A results from a database query and rows and/or columns can be added or extracted. B uses the information from A. What is an efficient way to insert/extract rows/columns without replacing the whole array?
To extract a row j from a matrix mxn I first transposed the matrix, and then multiplied it by a vector mx1 with all elements 0 apart from the element j which was 1. I extracted a column in the same way (without transposing this time though).
To extract a row j from a matrix mxn I first transposed the matrix, and then multiplied it by a vector mx1 with all elements 0 apart from the element j which was 1. I extracted a column in the same way (without transposing this time though).
