triangularMatrix-class | R Documentation |

The virtual class of triangular matrices,`"triangularMatrix"`

,
the package Matrix contains *square* (```
nrow ==
ncol
```

) numeric and logical, dense and sparse matrices, e.g.,
see the examples.
A main use of the virtual class is in methods (and C functions) that
can deal with all triangular matrices.

`uplo`

:String (of class

`"character"`

). Must be either "U", for upper triangular, and "L", for lower triangular.`diag`

:String (of class

`"character"`

). Must be either`"U"`

, for unit triangular (diagonal is all ones), or`"N"`

for non-unit. The diagonal elements are not accessed internally when`diag`

is`"U"`

. For`denseMatrix`

classes, they need to be allocated though, such that the length of the`x`

slot does not depend on`diag`

.`Dim`

,`Dimnames`

:The dimension (a length-2

`"integer"`

) and corresponding names (or`NULL`

), inherited from the`Matrix`

, see there.

Class `"Matrix"`

, directly.

There's a C function `triangularMatrix_validity()`

called by the internal validity checking functions.

Currently, `Schur`

, `isSymmetric`

and
`as()`

(i.e. `coerce`

) have methods with
`triangularMatrix`

in their signature.

`isTriangular()`

for testing any matrix for triangularity;
classes `symmetricMatrix`

, and, e.g.,
`dtrMatrix`

for numeric *dense* matrices, or
`ltCMatrix`

for a logical *sparse* matrix
subclass of `"triangularMatrix"`

.

showClass("triangularMatrix") ## The names of direct subclasses: scl <- getClass("triangularMatrix")@subclasses directly <- sapply(lapply(scl, slot, "by"), length) == 0 names(scl)[directly] (m <- matrix(c(5,1,0,3), 2)) as(m, "triangularMatrix")

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