q* ( u v -- u*v )

Vocabulary

math.quaternions

Inputs

u	a quaternion
v	a quaternion

Outputs

u*v	a quaternion

Word description

Multiply quaternions.

Examples

USING: math.quaternions prettyprint ; { 0 1 0 0 } { 0 0 1 0 } q* .
{ 0 0 0 1 }

Definition

USING: combinators kernel math.quaternions.private math.vectors
;

IN: math.quaternions

: q* ( u v -- u*v )
    {
        [
            [ { 1 0 0 0 } vshuffle ] [ { 1 1 2 3 } vshuffle ]
            bi* v*
        ]
        [
            [ { 2 1 2 3 } vshuffle ] [ { 2 0 0 0 } vshuffle ]
            bi* v* v+
        ]
        [
            [ { 3 2 3 1 } vshuffle ] [ { 3 3 1 2 } vshuffle ]
            bi* v* v+
        ]
        [
            [ { 0 3 1 2 } vshuffle ] [ { 0 2 3 1 } vshuffle ]
            bi* v* v-
        ]
    } 2cleave (q*sign) ; inline