buildTmat {matlib} | R Documentation |
Build/Get transformation matrices
Description
Recover the history of the row operations that have been performed. This function combines the transformation matrices 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 class 'trace'
as.matrix(x, ...)
## S3 method for class 'trace'
print(x, ...)
Arguments
x |
a matrix A, joined with a vector of constants, b, that has been passed to
|
all |
logical; print individual transformation ies? |
... |
additional arguments |
Value
the transformation matrix or a list of individual transformation matrices
Author(s)
Phil Chalmers
See Also
Examples
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 matrices
buildTmat(Abt, TRUE)
# invert transformation matrix to reverse operations
inv(T) %*% Abt
# gaussian elimination
(soln <- gaussianElimination(A, b))
T <- buildTmat(soln)
inv(T) %*% soln
[Package matlib version 0.9.8 Index]