В Thu, 03 Jan 2008 09:22:12 -0800 Roger Hui <[EMAIL PROTECTED]> пишет:
> a. Are you solving for X or for Y? X > > b. In addition to knowing that there are only around 100 non-zero > entries per row, do you know anything more about the matrix A? > Is it a band matrix, for instance? > > See in the dictionary the entry for $., in particular > http://www.jsoftware.com/help/dictionary/d211.htm#sparse%20linear%20algebra > However neither +/ .* nor %. in the public version of J > are up to dealing with the matrix A you described. No, it's not a band matrix. This matrix is closer to the Connection matrix of Directed Graphs. Thanks for the link. So, if %. isn't realized for the sparse matrix, it looks like the task should be done using the iterative method. > > c. With arrays of this size you should avoid CSV or anything > that requires repeated conversions into 4- or 8-byte machine > integers and 8-byte machine floating point numbers. I believe the conversion will not be present if I use mapped files as a matrix, will it? Nick. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
