### The Maxima on-line user's manual

Algebra Calculator

#### Identfor

Function: identfor (<M>)

Function: identfor (<M>, <fld>) Return an identity matrix that has the same shape as the matrix <M>. The diagonal entries of the identity matrix are the multiplicative identity of the field <fld>; the default for <fld> is <generalring>.

The first argument <M> should be a square matrix or a non-matrix. When <M> is a matrix, each entry of <M> can be a square matrix - thus <M> can be a blocked Maxima matrix. The matrix can be blocked to any (finite) depth.

See also `zerofor`

```(%o1)                                true
(%i2) ```

### Related Examples

##### identfor-invert-matrix

R:matrix([a11, a12, a...

I:identfor(R);

invert(I-R);

Calculate

##### identfor-invert-matrix-ratsimp

A: matrix([-Ra/La,-k/...

B: matrix([1/La,0],[0...

sol1: invert(s*identf...

Calculate

##### identfor-mat_trace-matrix-sum-trace

strain(u) := matrix([...

stress(e) := b*mat_tr...

sum(sum(strain[i][j] ...

Calculate

##### identfor-invert-matrix

R:matrix([a11, a12, a...

I:identfor(R);

invert(I-R);

Calculate

##### identfor-mat_trace-matrix-sum-trace

strain(u) := matrix([...

stress(e) := b*mat_tr...

sum(sum(strain(u)[i][...

Calculate

##### identfor-mat_trace-matrix-trace

strain(u) := matrix([...

stress(e) := b*mat_tr...

Calculate

##### identfor-invert-matrix

A: matrix([-Ra/La,-k/...

B: matrix([1/La,0],[0...

sol1: invert(s*identf...

Calculate

##### identfor-matrix

A: matrix([-Ra/La,-k/...

B: matrix([1/La,0],[0...

s*identfor(A)-A;

Calculate

##### identfor-invert-matrix

A: matrix([-Ra/La,-k/...

B: matrix([1/La,0],[0...

sol1: invert(s*identf...

Calculate

##### identfor-invert-matrix

R:matrix([a11, a12, a...

I:identfor(R);

invert(R);

Calculate