diag

Creates a diagonal matrix from a sequence of numbers.

Syntax

• diag(a[, [b, ...]])

  • a, b, ... are numbers

• diag(X)

  • X is a vector or a list of numbers

Description

• If a, b, ... are numbers, then diag(a, b, ...) is the diagonal matrix having a, b, ... on the diagonal.

• If X is a vector or a list of numbers, then diag(X) is the diagonal matrix having the elements of X on the diagonal.

Examples

diag(4, 1, 2, 1)

⎛4  0  0  0⎞
⎜0  1  0  0⎟
⎜0  0  2  0⎟
⎝0  0  0  1⎠

diag(❨7, 2, 1, 1, −2❩)

⎛ 7   0   0   0   0⎞
⎜ 0   2   0   0   0⎟
⎜ 0   0   1   0   0⎟
⎜ 0   0   0   1   0⎟
⎝ 0   0   0   0  −2⎠

diag('(0, 1, 2, 1, 0, 1))

⎛0  0  0  0  0  0⎞
⎜0  1  0  0  0  0⎟
⎜0  0  2  0  0  0⎟
⎜0  0  0  1  0  0⎟
⎜0  0  0  0  0  0⎟
⎝0  0  0  0  0  1⎠

See also

• IsDiagonal

• MainDiagonal

• Creating a matrix (conceptual)