Class "spam"

Description

The spam class is a representation of sparse matrices.

Objects from the Class

Objects can be created by calls of the form new("spam", entries, colindices, rowpointes, dimension). The standard "old Yale sparse format" is used to store sparse matrices.
The matrix x is stored in row form. The first element of row i is x@rowpointers[i]. The length of row i is determined by x@rowpointers[i+1]-x@rowpointers[i]. The column indices of x are stored in the x@colindices vector. The column index for element x@entries[k] is x@colindices[k].

Slots

entries:

Object of class "numeric" contains the nonzero values

colindices:

Object of class "integer" ordered indices of the nonzero values

rowpointers:

Object of class "integer" pointer to the beginning of each row in the arrays entries and colindices

dimension:

Object of class "integer" ~~

Methods

as.matrix

signature(x = "spam"): transforming a sparse matrix into a regular matrix.

as.spam

signature(x = "spam"): cleaning of a sparse matrix.

[<-

signature(x = "spam", i,j, value): assigning a sparse matrix. The negative vectors are not implemented yet.

[

signature(x = "spam", i, j): subsetting a sparse matrix. The negative vectors are not implemented yet.

%*%

signature(x, y): matrix multiplication, all combinations of sparse with full matrices or vectors are implemented.

c

signature(x = "spam"): vectorizes the sparse matrix and takes account of the zeros. Hence the lenght of the result is prod(dim(x)).

cbind

signature(x = "spam"): binds sparse matrices.

chol

signature(x = "spam"): see chol for details.

diag

signature(x = "spam"): see diag for details.

dim<-

signature(x = "spam"): truncates or augments the matrix see dim for details.

dim

signature(x = "spam"): gives the dimension of the sparse matrix.

image

signature(x = "spam"): see image for details.

display

signature(x = "spam"): see display for details.

length<-

signature(x = "spam"): Is not implemented and causes an error.

length

signature(x = "spam"): gives the number of non-zero elements.

lower.tri

signature(x = "spam"): see lower.tri for details.

Math

signature(x = "spam"): see Math for details.

Math2

signature(x = "spam"): see Math2 for details.

norm

signature(x = "spam"): calculates the norm of a matrix.

plot

signature(x = "spam", y): same functionality as the ordinary plot.

print

signature(x = "spam"): see print for details.

rbind

signature(x = "spam"): binds sparse matrices.

solve

signature(a = "spam"): see solve for details.

summary

signature(object = "spam"): small summary statement of the sparse matrix.

Summary

signature(x = "spam"): All functions of the Summary class (like min, max, range...) operate on the vector x@entries and return the result thereof. See Examples.

t

signature(x = "spam"): transpose of a sparse matrix.

upper.tri

signature(x = "spam"): see lower.tri for details.

Details

The compressed sparse row (CSR) format is often described with the vectors a, ia, ja. To be a bit more comprehensive, we have chosen longer slot names.

Note

The slots colindices and rowpointers are tested for proper integer assignments. This is not true for entries.

Author(s)

Reinhard Furrer, some of the Fortran code is based on A. George, J. Liu, E. S. Ng, B.W Peyton and Y. Saad (alphabetical)

Examples

showMethods("as.spam")

smat <- diag.spam(runif(15))
range(smat)
cos(smat)