http://livedocs.adobe.com/ Macromedia LiveDocs - online documentation with user feedback. Copyright 2009, Macromedia, Inc. 2009-11-25T11:09:10 en-us http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/flash/geom/Matrix.html#79516 I submitted my previous remarks too quickly. It's mathematically equivalent to think of the matrix elements as<br /><br />a b 0<br />c d 0<br />t(x) t(y) 1<br /><br />as long as you use pre-multiplied row vectors and treat concatenation as a post-multiply operation. So take your pick; just be consistent.<br /><br />The important point is that the b and c elements are transposed in Adobe's documentation.<br /><br />Also, I wrote that this error had persisted since AS 2.0. What I meant to say was that it had persisted since Flash 8.<br /><br />Happy hacking! mmcaulay 0 0 2008-01-15T10:28:51 http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/flash/geom/Matrix.html#79199 BaconTastesGood is right: the Matrix documentation is incorrect regarding the order of the elements. The correct order is:<br /><br />a c t(x)<br />b d t(y)<br />0 0 1<br /><br />There is a nice interactive tutorial here: http://imm.sheridanc.on.ca/imm2006/macgillm/tutorial/<br /><br />It's not stated explicitly anywhere in the documentation but flash uses column vectors (not row vectors). So the transformation of a vector by a matrix is a post-multiply operation: x' = Ax.<br /><br />A consequence is that the operation A concat B is equivalent to premultiplying A by B: A' = BA, *not* A' = AB.<br /><br />For casual use this may not matter. But for anyone else out there playing tricksy matrix games, I hope this saves you a little time.<br /><br />Adobe, it's time to update the Matrix docs! This error has persisted since AS2.0. mmcaulay 0 0 2008-01-04T16:34:07