# Pose\_add - What's the meaning of \* and the effect on Rotations?

**URL:** <https://forum.universal-robots.com/t/pose-add-whats-the-meaning-of-and-the-effect-on-rotations/19207>\
**Category:** URScript\
**Created:** [February 11, 2022, 2:20pm UTC](https://forum.universal-robots.com/t/pose-add-whats-the-meaning-of-and-the-effect-on-rotations/19207 "2022-02-11T14:20:17Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![anon39341532](https://avatars.discourse-cdn.com/v4/letter/a/aca169/32.png) [@anon39341532](https://forum.universal-robots.com/u/anon39341532)\
**Post date:** [February 11, 2022, 2:20pm UTC](https://forum.universal-robots.com/t/pose-add-whats-the-meaning-of-and-the-effect-on-rotations/19207/1 "2022-02-11T14:20:17Z")

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The UR-Script documentation says that for the rotation triplet, the effect of the pose\_add command is p\_3.R = p\_1.R \* p\_2.R.

But what is this supposed to mean? I suppose this isn’t meant to be a scalar multiplication, as the result has to be 3 numbers again. But what else happens? Component-wise multiplication doesn’t make sense as well. The given example suggests that the components are simply added as well, but I’m not sure that this holds in every case.

What I first thought was that the rotation vector actually represents a rotation matrix, and the two rotation matrices are then multiplied - is that the correct behaviour of the pose\_add command?

As an addendum, in what regards does the pose\_add command differ from the pose\_trans command?

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**Author:** ![anon39341532](https://avatars.discourse-cdn.com/v4/letter/a/aca169/32.png) [@anon39341532](https://forum.universal-robots.com/u/anon39341532)\
**Post date:** [March 1, 2022, 10:45am UTC](https://forum.universal-robots.com/t/pose-add-whats-the-meaning-of-and-the-effect-on-rotations/19207/2 "2022-03-01T10:45:56Z")

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I guess the command “Pose\_add” should have a clearly defined and implemented behaviour, but the script manual doesn’t go into details on this.

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**Author:** ![mvrooij](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/mvrooij/32/2151_2.png) [@mvrooij](https://forum.universal-robots.com/u/mvrooij)\
**Post date:** [August 28, 2022, 9:43pm UTC](https://forum.universal-robots.com/t/pose-add-whats-the-meaning-of-and-the-effect-on-rotations/19207/3 "2022-08-28T21:43:02Z")

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The multiplication is actually a 3x3 matrix multiply of two rotation matrices. The poses are first converted to matrix notation and then the translation parts are added and the rotation parts multiplied, giving a new matrix. This is then translated into a pose.