<div class="gmail_quote">On Wed, Jan 5, 2011 at 22:02, S V N Vishwanathan <span dir="ltr"><<a href="mailto:vishy@stat.purdue.edu">vishy@stat.purdue.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div id=":38t">I mean a two dimensional array. Basically my parameter vector is of the<br>
form<br>
<br>
vec = (vec1^t, vec2^t, vec3^t,...veck^t)^t<br>
<br>
which I represent as a Petsc Vector. In my objective function<br>
calculation I am given a matrix X and need to compute<br>
<br>
fx = (X.vec1, X.vec2, ..., X.veck)^t</div></blockquote></div><br><div>1. How big is "k"?</div><div><br></div><div>2. Since each vec1,vec2,... is the same size, this is likely to produce poor memory performance. If you care about speed, I suggest interlacing the values in vec1,...,veck. In that case, you can create an MAIJ matrix that acts on this "multi-vector".</div>