```
# NOT RUN {
showClass("dtrMatrix")
example("dtrMatrix-class", echo=FALSE)
(p1 <- as(T2, "dtpMatrix"))
str(p1)
(pp <- as(T, "dtpMatrix"))
ip1 <- solve(p1)
stopifnot(length(p1@x) == 3, length(pp@x) == 3,
p1 @ uplo == T2 @ uplo, pp @ uplo == T @ uplo,
identical(t(pp), p1), identical(t(p1), pp),
all((l.d <- p1 - T2) == 0), is(l.d, "dtpMatrix"),
all((u.d <- pp - T ) == 0), is(u.d, "dtpMatrix"),
l.d@uplo == T2@uplo, u.d@uplo == T@uplo,
identical(t(ip1), solve(pp)), is(ip1, "dtpMatrix"),
all.equal(as(solve(p1,p1), "diagonalMatrix"), Diagonal(2)))
# }
```

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