IdentityMatrix

IdentityMatrix[n]

gives the nn identity matrix.

Details and Options

Examples

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Basic Examples  (1)

Construct a 3×3 identity matrix:

Scope  (1)

Construct a 3×4 identity matrix:

Options  (1)

WorkingPrecision  (1)

Create a machine-precision identity matrix:

Properties & Relations  (3)

Use DiagonalMatrix for general diagonal matrices:

The KroneckerProduct of a matrix with the identity matrix is a block diagonal matrix:

The WorkingPrecision option is equivalent to creating the matrix, then applying N:

Possible Issues  (1)

IdentityMatrix gives a matrix with dense storage. SparseArray is more compact:

The SparseArray representation uses a fraction of the memory:

For matrix and arithmetic operations they are effectively equal:

Introduced in 1988
 (1.0)
 |
Updated in 2008
 (7.0)