<div class="gmail_quote">On Wed, Aug 31, 2011 at 07:52, Dominik Szczerba <span dir="ltr"><<a href="mailto:dominik@itis.ethz.ch">dominik@itis.ethz.ch</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div id=":3x3">I am getting the below cited error for a big linear problem. Would<br>
that mean int overflow and indicate the need for<br>
--with-64-bit-indices? </div></blockquote><div><br></div><div>Yes, likely.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div id=":3x3">Obviously it will elevate the memory<br>
requirements, but will it also reduce the performance?<br></div></blockquote><div><br></div><div>Try it. Performance for sparse linear algebra is mostly limited by memory already. Using 64-bit indices increases the cost per nonzero in AIJ format, sizeof(PetscScalar)+sizeof(PetscInt), typically from 12 to 16 bytes. If you use BAIJ, the 64-bit indices will make much less difference.</div>
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