Generate a 4x4 transformation matrix which can pass into `multmatrix`

to rotate the child element about the axis of the coordinate system or around an arbitrary axis.

**Since:** 1.1

## Parameters

`a`

: If it's`[deg_x, deg_y, deg_z]`

, the rotation is applied in the order`x`

,`y`

,`z`

. If it's`[deg_x, deg_y]`

, the rotation is applied in the order`x`

,`y`

. If it's`[deg_x]`

, the rotation is only applied to the`x`

axis. If it's an number, the rotation is only applied to the`z`

axis or an arbitrary axis.`v`

: A vector allows you to set an arbitrary axis about which the object will be rotated. When`a`

is an array, the`v`

argument is ignored.

## Examples

```
include <m_rotation.scad>;
point = [20, 0, 0];
a = [0, -45, 45];
hull() {
sphere(1);
multmatrix(m_rotation(a))
translate(point)
sphere(1);
}
```

```
include <m_rotation.scad>;
v = [10, 10, 10];
hull() {
sphere(1);
translate(v)
sphere(1);
}
p = [10, 10, 0];
for(i = [0:20:340]) {
multmatrix(m_rotation(a = i, v = v))
translate(p)
sphere(1);
}
```