diag

---
description: Guidelines for diag
globs: **/*
---


 Usage

The diag function is used to either construct a diagonal
matrix from a vector, or return the diagonal elements of a
matrix as a vector. The general syntax for its use is

    y = diag(x,n)

If x is a matrix, then y returns the n-th diagonal. If n is
omitted, it is assumed to be zero. Conversely, if x is a
vector, then y is a matrix with x set to the n-th diagonal.


 Examples

Here is an example of diag being used to extract a diagonal
from a matrix.

  --> A = int32(10*rand(4,5))

  A =
    5  8  8  3  6
    4  8  4  3  7
    9  5  8  4  2
    1  0 10  0  4

  --> diag(A)

  ans =
   5
   8
   8
   0

  --> diag(A,1)

  ans =
   8
   4
   4
   4

Here is an example of the second form of diag, being used to
construct a diagonal matrix.

  --> x = int32(10*rand(1,3))

  x =
   6 3 9

  --> diag(x)

  ans =
   6 0 0
   0 3 0
   0 0 9

  --> diag(x,-1)

  ans =
   0 0 0 0
   6 0 0 0
   0 3 0 0
   0 0 9 0


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* Array_Generation_and_Manipulations
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