# ltrMatrix-class: Triangular Dense Logical Matrices In Matrix: Sparse and Dense Matrix Classes and Methods

## Description

The `"ltrMatrix"` class is the class of triangular, dense, logical matrices in nonpacked storage. The `"ltpMatrix"` class is the same except in packed storage.

## Slots

`x`:

Object of class `"logical"`. The logical values that constitute the matrix, stored in column-major order.

`uplo`:

Object of class `"character"`. Must be either "U", for upper triangular, and "L", for lower triangular.

`diag`:

Object of class `"character"`. Must be either `"U"`, for unit triangular (diagonal is all ones), or `"N"`; see `triangularMatrix`.

`Dim`,`Dimnames`:

The dimension (a length-2 `"integer"`) and corresponding names (or `NULL`), see the `Matrix` class.

`factors`:

Object of class `"list"`. A named list of factorizations that have been computed for the matrix.

## Extends

Both extend classes `"ldenseMatrix"` and `"triangularMatrix"`, directly; further, class `"Matrix"`, `"lMatrix"` and others, indirectly. Use `showClass("ltrMatrix")`, e.g., for details.

## Methods

Currently, mainly `t()` and coercion methods (for `as(.)`; use, e.g., `showMethods(class="ltpMatrix")` for details.

Classes `lgeMatrix`, `Matrix`; function `t`
 ```1 2 3 4 5 6 7 8``` ```showClass("ltrMatrix") str(new("ltpMatrix")) (lutr <- as(upper.tri(matrix(,4,4)), "ltrMatrix")) str(lutp <- as(lutr, "ltpMatrix"))# packed matrix: only 10 = (4+1)*4/2 entries !lutp ## the logical negation (is *not* logical triangular !) ## but this one is: stopifnot(all.equal(lutp, as(!!lutp, "ltpMatrix"))) ```