Extracts all nonzero diagonals from the m-by-n matrix A. B is a min(m,n)-by-p matrix whose columns are the p nonzero diagonals of A.
spdiags(A)
A min(m,n)-by-p matrix, usually (but not necessarily) full, whose columns are the diagonals of A.
A vector of length p whose integer components specify the diagonals in A.
An m-by-n matrix with nonzero elements located on p diagonals.
John C. Nash (nashjc@uottawa.ca)
Compared to the original Matlab implementation: 1) it does not handle the case with more than one input, and 2) (m > n) matrices give the B matrix columns in a different order, but the d vector of indices will also be changed accordingly, so the set of columns is OK, just ordered differently
dta <- c(0, 5, 0, 10, 0, 0, 0, 0, 6, 0, 11, 0, 3, 0, 0,
7, 0, 12, 1, 4, 0, 0, 8, 0, 0, 2, 5, 0, 0, 9)
A1 <- matrix(dta, nrow=5, ncol=6, byrow=TRUE)
print(A1)
res1 <- spdiags(A1)
print(res1)
Run the code above in your browser using DataLab