Remembering an earlier discussion of symmetric arrays (not just matrices), we could ask for efficient ways of dealing with them/representing them. What can be done with existing facilities?
About matrices, Gilbert Strang comments in Linear Algebra and Its Applications: "Symmetric matrices appear in every subject whose laws are fair. 'Each action has an equal and opposite reaction.' The entry a_ij that gives the action of i onto j is matched by a_ji." On Thu, 31 Aug 2006, Fraser Jackson wrote: | There are many problems where for a matrix a either the following | | a fn"1 1 / a | | or | | | a f . g |: a | | generate a symmetric matrix. | | | I could well do with the saving of half the time on a computation. | | 1. Has anyone good suggestions for handling this? | 2. Isn't this such a common problem that some way of telling the | interpreter to only do one triangle should be constructed? | | Fraser Kip Murray Math, UofHouston [EMAIL PROTECTED] http://www.math.uh.edu/~km ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
