# llRot2Angle

 LSL Portal
Function: float llRot2Angle( rotation rot );
 171 Function ID 0 Forced Delay 10 Energy

Returns a float that is the rotation angle represented by rot

 • rotation rot

Use in conjunction with llRot2Axis.
To undo use llAxisAngle2Rot.

## Caveats

This always returns a positive angle <= PI radians, that is, it is the unsigned minimum angle. A rotation of 3/2 PI radians (270 degrees) will return an angle of PI / 2 radians, not -PI / 2.

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## Examples

### Functions

 • llAxisAngle2Rot • llRot2Axis • llRot2Up • llRot2Fwd • llRot2Left • llAngleBetween – Similar functionality.

## Deep Notes

### Reference Implementation

 ```float Rot2Angle(rotation a)//simple but turns out to not be very accurate. { return 2.0 * llAcos(llSqrt((a.s * a.s) / (a.x * a.x + a.y * a.y + a.z * a.z + a.s * a.s)); } ``` ```float Rot2Angle(rotation r)//more complex implementation but more accurate, and reasonably fast. { float s2 = r.s * r.s; // square of the s-element float v2 = r.x * r.x + r.y * r.y + r.z * r.z; // sum of the squares of the v-elements if (s2 < v2) // compare the s-component to the v-component return 2.0 * llAcos(llSqrt(s2 / (s2 + v2))); // use arccos if the v-component is dominant if (v2) // make sure the v-component is non-zero return 2.0 * llAsin(llSqrt(v2 / (s2 + v2))); // use arcsin if the s-component is dominant return 0.0; // argument is scaled too small to be meaningful, or it is a zero rotation, so return zero }//Written by Moon Metty & Miranda Umino. Minor optimizations by Strife Onizuka ```

#### Signature

```function float llRot2Angle( rotation rot );
```