<div>The title of the paper advertises (states) that the method is closed form (expressed as a set of equations that can be directly evaluated to give the solution).</div><div><br></div><div>Within the paper, one important step of the method is done with a standard iterative (i.e. not closed-form) algorithm to find the eigenvalues of a 4x4 matrix.</div>
<div><br></div><div>So, the solution presented in the paper is not closed-form. The paper states that a closed-form solution for the eigenvalues of a 4x4 matrix exists, but it does not use the closed-form solution. It uses an iterative solution instead.</div>
<div><br></div><div>It wasn't until later (maybe 2002?) that someone finally published a fully closed-form solution. But VTK uses Horn's method, not the new method. People who are just using the method (rather than implementing it) probably will not care one way or the other... the two methods would give nearly identical answers.</div>
<div><br></div> - David<div><br><br><div class="gmail_quote">On Tue, Dec 6, 2011 at 3:17 PM, andon <span dir="ltr"><<a href="mailto:antoniod987@gmail.com" target="_blank">antoniod987@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I've not understood what do you mean for " it isn't a closed form solution as<br>
advertised." and "The complete closed-form solution was developed later.<br></blockquote></div></div>