spam.chol.NgPeyton-class {spam} | R Documentation

## Class "spam.chol.NgPeyton"

### Description

Result of a Cholesky decomposition with the `NgPeyton` method

### Objects from the Class

Objects are created by calls of the form `chol(x,method="NgPeyton", ...)` and should not be created directly with a `new("spam.chol.NgPeyton", ...)` call.
At present, no proper print method is defined. However, the factor can be transformed into a `spam` object.

### Methods

as.matrix

  `signature(x = "spam.chol.NgPeyton")`: Transform the factor into a regular matrix.

as.spam

  `signature(x = "spam.chol.NgPeyton")`: Transform the factor into a `spam` object.

backsolve

  `signature(r = "spam.chol.NgPeyton")`: solving a triangular system, see `solve`.

forwardsolve

  `signature(l = "spam.chol.NgPeyton")`: solving a triangular system, see `solve`.

c

  `signature(x = "spam.chol.NgPeyton")`: Coerce the factor into a vector.

determinant

  `signature(x = "spam.chol.NgPeyton")`: Calculates the determinant from the factor, see also `det`.

diag

  `signature(x = "spam.chol.NgPeyton")`: Extracts the diagonal entries.

dim

  `signature(x = "spam.chol.NgPeyton")`: Retrieve the dimension. Note that `"dim<-"` is not implemented.

display

  `signature(x = "spam.chol.NgPeyton")`: Transformation to a `spam` object and display, see also `display`.

image

  `signature(x = "spam.chol.NgPeyton")`: Transformation to a `spam` object and display, see also `image`.

length

  `signature(x = "spam.chol.NgPeyton")`: Retrieve the dimension. Note that `"length<-"` is not implemented.

ordering

  `signature(x = "spam.chol.NgPeyton")`: Retrieves the ordering, in `ordering`.

print

  `signature(x = "spam.chol.NgPeyton")`: Short description.

show

  `signature(object = "spam.chol.NgPeyton")`: Short description.

summary

  `signature(object = "spam.chol.NgPeyton")`: Description of the factor, returns (as a list) `nnzR`, `nnzcolindices`, the density of the factor `density`, and fill-in ratio `fillin`. For the use of the first two, see ‘Examples’ in `chol`.

t

  `signature(x = "spam.chol.NgPeyton")`: Transformation to a `spam` object and transposition.

chol

  `signature(x = "spam.chol.NgPeyton")`: Returns `x` unchanged.

### Author(s)

Reinhard Furrer

### References

Ng, E. G. and B. W. Peyton (1993), "Block sparse Cholesky algorithms on advanced uniprocessor computers", SIAM J. Sci. Comput., 14, pp. 1034-1056.

### See Also

`print.spam` `ordering` and `chol`

### Examples

    x <- spam( c(4,3,0,3,5,1,0,1,4),3)
    cf <- chol( x)
    cf
    as.spam( cf)

    # Modify at own risk...
    slotNames(cf)

[Package spam version 2.2-2 Index]