pan class="bold"><strong>R</strong></span></em></span>
        by <span class="emphasis"><em><span class="bold"><strong>R<sup>3</sup></strong></span></em></span> (the quaternionic
        multiplication as then a special form, as given here). This function therefore
        builds a quaternion from this representation, with the <span class="emphasis"><em><span class="bold"><strong>R<sup>3</sup></strong></span></em></span> component given in usual <span class="emphasis"><em><span class="bold"><strong>R<sup>3