polyMatrix: diag.pMatrix – R documentation

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diag.pMatrix

Extracts the diagonal of a polyMatrix, or constructs a diagonal polyMatrix

Description

If the input is a polyMatrix then the output is its diagonal. If the input is a vector then the output is a diagonal matrix.

Usage

## S3 method for class 'list'
diag(x, nrow=NULL, ncol=NULL, names=NULL, type=CLASS_LIST, ...)
## S3 method for class 'polyMatrix'
diag(x, nrow=NULL, ncol=NULL, names=NULL, type=CLASS_LIST, ...)

Arguments

`v`	the `list` class input material for the diagonal matrix
`nrow`	number of rows in the output object
`ncol`	number of columns in the output object
`pm`	the `polyMatrix` class input matrix
`type`	the required form and class of the result: `CLASS_LIST` or `CLASS_MATRIX`

Details

The diag has two different applications. When the class of the first input parameter is

'list', then returns a polyMatrix with the given diagonal and zero off-diagonal entries.
'polyMatrix', then extracts the diagonal.

Note. In the first case the elements of the list must be polynomial class objects. In the second case the result is a list or polyMatrix class object determined by the value of the type parameter.

Value

The returned value is a

`list`	class object, when it extracts the diagonal from a `polyMatrix`, and the value of `type` isn't '`polyMatrix`'.
`polyMatrix`	class object, when builds a matrix from the given diagonal or when returns the diagonal of a `polyMatrix`, and the `type="polyMatrix"`.

Examples

# ---
# case of real matrices

m<-matrix(1:12,3,4)
m
diag(m) # first type usage

v<-c(1,5,9) # second type usage
diag(v)
diag(v,4)
diag(v,4,2)
diag(v,ncol=4)

# ---
# case of polynomial matrices

# first kind usage: catch the diagonal elements

px<-polyMgen.d(3,3,rawData=ch2pn(
     c("-3 + z^2","2 + 4*z","-z^2",
       "1","2","3 + z",
       "2*z","0","2 - 3*z"),"z"),byrow=TRUE)
class(px) # "polyMdlist" "polyMatrix"
px

w<-diag(px) # the default: type="list"
class(w) # "list"
# List of 3
# $ :Class 'polynomial'  num [1:3] -3 0 1
# $ :Class 'polynomial'  num 2
# $ :Class 'polynomial'  num [1:2] 2 -3
w

w<-diag(px,type="polyMatrix")
class(w) # "polyMdlist" "polyMatrix"
w


# second kind usage: compose a diagonal polyMatrix

ci<-c(4,1,3,2)
v<-vector("list",length(ci))
for(i in 1:length(ci))
  v[[i]]<-polynom::polynomial(c(rep(0,ci[i]),1))
class(v) # "list"
v

diag(v)
diag(v,4)
diag(v,3)
diag(v,5)
diag(v,3,5)

pd<-diag(v,4,5)
class(pd) # "polyMdlist" "polyMatrix"
pd

# clean up
# rm(ci, i, m, pd, px, v, w)

polyMatrix

Infrastructure for Manipulation Polynomial Matrices

v0.3.1

MIT + file LICENSE

Authors

Tamas Prohle [aut], Peter Prohle [aut], Nikolai Ryzhkov [aut, cre], Ildiko Laszlo [aut] (<https://orcid.org/0000-0003-2324-8183>), Ulas Onat Alakent [ctb]

Initial release