crossprod(x, y = NULL) tcrossprod(x, y = NULL)
x | matrix or vector, numeric or complex. Missing values (NA) are allowed. |
y |
matrix or vector, numeric or complex. Must have the same number of
rows as x. If not specified or NULL (the default),
x is used. Also, for tcrossprod, y must have
the same number of columns as x.
Missing values (NA) are allowed. |
crossprod | returns a matrix representing the cross product of x and y, defined as t(x) %*% y, where %*% is matrix multiplication and t is transposition. Thus the [i,j]th element of the result is sum(x[,i]*y[,j]). |
tcrossprod | returns a matrix representing the cross product of t(x) and t(y), defined as x %*% t(y), where %*% is matrix multiplication and t is transposition. Thus the [i,j]th element of the result is sum(x[i,]*y[j,]). |
amat <- matrix(c(19,8,11,2,18,17,15,19,10), nrow = 3) crossprod(amat) # if amat has dimensions of n(rows) and p(cols) # the resultant matrix will be p by p bmat <- c(9, 5, 14) crossprod(amat, bmat)tcrossprod(1:3, 11:13) # same as outer(1:3, 11:13)