# buildTmat

From matlib v0.9.2
by Michael Friendly

##### Build/Get tranformation matricies

Recover the history of the row operations that have been performed. This function combines the transformation matricies into a single transformation matrix representing all row operations or may optionally print all the individual operations which have been performed.

##### Usage

`buildTmat(x, all = FALSE)`# S3 method for trace
as.matrix(x, ...)

# S3 method for trace
print(x, ...)

##### Arguments

- x
a matrix A, joined with a vector of constants, b, that has been passed to

`gaussianElimination`

or the row operator functions- all
logical; print individual tranformation matricies?

- ...
additional arguments

##### Value

the tranformation matrix or a list of individual transformation matricies

##### See Also

##### Examples

```
# NOT RUN {
A <- matrix(c(2, 1, -1,
-3, -1, 2,
-2, 1, 2), 3, 3, byrow=TRUE)
b <- c(8, -11, -3)
# using row operations to reduce below diagonal to 0
Abt <- Ab <- cbind(A, b)
Abt <- rowadd(Abt, 1, 2, 3/2)
Abt <- rowadd(Abt, 1, 3, 1)
Abt <- rowadd(Abt, 2, 3, -4)
Abt
# build T matrix and multiply by original form
(T <- buildTmat(Abt))
T %*% Ab # same as Abt
# print all transformation matricies
buildTmat(Abt, TRUE)
# invert transformation matrix to reverse operations
inv(T) %*% Abt
# gaussian elimination
(soln <- gaussianElimination(A, b))
T <- buildTmat(soln)
inv(T) %*% soln
# }
```

*Documentation reproduced from package matlib, version 0.9.2, License: GPL (>= 2)*

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