diag
Diagonal uncertain matrices; diagonals of an uncertain matrix
Description
Examples
Create Uncertain Diagonal Matrix from Uncertain Vector
Create an uncertain matrix MV
in which the diagonal elements are the elements of an uncertain vector V
, and the off-diagonal elements are all 0. First, create the uncertain vector V
.
a = ureal('a',10); b = ureal('b',5); V = [1+a 2 3-b 4]
Uncertain matrix with 1 rows and 4 columns. The uncertainty consists of the following blocks: a: Uncertain real, nominal = 10, variability = [-1,1], 1 occurrences b: Uncertain real, nominal = 5, variability = [-1,1], 1 occurrences Type "V.NominalValue" to see the nominal value and "V.Uncertainty" to interact with the uncertain elements.
V
is a 1-by-4 umat
uncertain matrix, or in other words, an uncertain row vector with four elements. Create MV
such that the diagonals of MV
are the elements of V
.
MV = diag(V)
Uncertain matrix with 4 rows and 4 columns. The uncertainty consists of the following blocks: a: Uncertain real, nominal = 10, variability = [-1,1], 1 occurrences b: Uncertain real, nominal = 5, variability = [-1,1], 1 occurrences Type "MV.NominalValue" to see the nominal value and "MV.Uncertainty" to interact with the uncertain elements.
To verify that MV
is a diagonal matrix, examine its nominal value.
MV.NominalValue
ans = 4×4
11 0 0 0
0 2 0 0
0 0 -2 0
0 0 0 4
Next, create a matrix in which V
forms the elements of the first diagonal below the main diagonal.
MV1 = diag(V,-1)
Uncertain matrix with 5 rows and 5 columns. The uncertainty consists of the following blocks: a: Uncertain real, nominal = 10, variability = [-1,1], 1 occurrences b: Uncertain real, nominal = 5, variability = [-1,1], 1 occurrences Type "MV1.NominalValue" to see the nominal value and "MV1.Uncertainty" to interact with the uncertain elements.
MV1.NominalValue
ans = 5×5
0 0 0 0 0
11 0 0 0 0
0 2 0 0 0
0 0 -2 0 0
0 0 0 4 0
Extract Diagonal Elements of Uncertain Matrix
Obtain a vector by extracting the diagonal elements of an uncertain matrix. First, create an uncertain matrix.
a = ureal('a',10); b = ureal('b',5); M = [1+a 2 3+b; 4 5+a 6; 7 8 9]
Uncertain matrix with 3 rows and 3 columns. The uncertainty consists of the following blocks: a: Uncertain real, nominal = 10, variability = [-1,1], 2 occurrences b: Uncertain real, nominal = 5, variability = [-1,1], 1 occurrences Type "M.NominalValue" to see the nominal value and "M.Uncertainty" to interact with the uncertain elements.
M
is a 3-by-3 uncertain matrix. Extract the diagonals of M
into a three-element column vector.
VM = diag(M)
Uncertain matrix with 3 rows and 1 columns. The uncertainty consists of the following blocks: a: Uncertain real, nominal = 10, variability = [-1,1], 1 occurrences Type "VM.NominalValue" to see the nominal value and "VM.Uncertainty" to interact with the uncertain elements.
VM
is a 3-by-1 umat
, or an uncertain column vector. Note that V
depends only on the uncertain parameter a
, because the diagonal elements of M
do not depend on b.
Next, extract a vector containing the elements of the first diagonal below the main diagonal of M
.
VM1 = diag(M,-1)
Uncertain matrix with 2 rows, 1 columns, and no uncertain blocks. Type "VM1.NominalValue" to see the nominal value and "VM1.Uncertainty" to interact with the uncertain elements.
This vector contains no uncertain elements at all. Examine its values.
VM1.NominalValue
ans = 2×1
4
8
Input Arguments
V
— Uncertain vector
umat
object
Uncertain vector, specified as a umat
object with dimensions
1-by-N (row vector) or N-by-1 (column
vector).
M
— Uncertain matrix
umat
object
Uncertain matrix, specified as a umat
object.
K
— Index of diagonal
0 (default) | integer
Index of diagonal, specified as an integer. K
= 0 represents
the main diagonal, K
> 0 is above the main diagonal, and
K
< 0 is below the main diagonal.
Output Arguments
VM
— Uncertain column vector
umat
object
Uncertain column vector, returned as a umat
object. The elements of
VM
are the diagonal elements of the input matrix
M
.
Version History
Introduced before R2006a
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