buildTmat | R Documentation |
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.
buildTmat(x, all = FALSE) ## S3 method for class 'trace' as.matrix(x, ...) ## S3 method for class 'trace' print(x, ...)
x |
a matrix A, joined with a vector of constants, b, that has been passed to
|
all |
logical; print individual transformation ies? |
... |
additional arguments |
the transformation matrix or a list of individual transformation matrices
Phil Chalmers
echelon
, gaussianElimination
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
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