binary-matrix

I want to multiply a 8x8 binary matrix represented as a unsigned 64 bit integer by a 8 bit vector represented by a unsigned char. However, due to some other issues the matrix must be ordered by columns, ergo there's no easy matching of bytes for easy multiplication. Any idea how to speed up such a calculation? Every operation counts for I need billions of such calculations made. The multiplications are made over a 2 element field (F-2). With this matrix and vector representation, it helps to do matrix multiplication this way: (col 1 ... col 8 ) * (v 1 ... v 8 ) T = col 1 * v 1 + ... + col 8 *

How to generate a binary matrix for all possible permutations of 'i' variables X, where " i " can be any number between 1 and infinite. Resultant matrix will have 2^ i unique rows. For i=2 , variables x1, x2 each with a possible value of 1 or 0, so the resultant matrix would be: X1 X2 0 0 0 1 1 0 1 1 Is there any function in R to generate ? I tried with below function: matrix(rbinom(160, 1, 0.5),ncol=5,nrow=(2^5)) But the result does not show all possible values. you can use expand.grid : expand.grid(c(0,1),c(0,1)) Var1 Var2 1 0 0 2 1 0 3 0 1 4 1 1 More generally, with 5 columns for example,