Good morning, my proposal for the implementation of linear iterative solvers (JIRA MATH-581) has raised some comments from Gilles and Luc, but I think no consensus has been reached on one issue raised by Gilles. Before submitting a new version of the corresponding classes, I'd like to make a new proposal.
Here is the thing. I have defined two exceptions, namely - NonSelfAdjointLinearOperatorException - NonPositiveDefiniteLinearOperatorException, the latter being typically raised when a vector x is found, such as x'.A.x <= 0, where A is the linear operator under consideration. Now, the constructor of this exception takes as input A and x (which I call the "offending vector"). There is a method to return a reference to A (which is a RealLinearOperator), and a method to return a deep copy of x, the reason for this is that x can either be a double[], or a RealVector. I agree with Gilles, for debugging purposes, it would probably be better to be able to trace the offending vector, hence to have the exception return a reference to this offending vector. But this is just not possible, since there is no unique type for this vector. Gilles pointed out that there is the method getData() in RealVector which would do the job, but there is no requirement in the contract of this method for this to be a shallow/deep copy. Is this a concern ? If not, then I could change the current method void copyOffendingVector(final double[] x) (where x is modified) into double[] getOffendingVector() but we would lose the track of the actual object which first raised the exception. Another option would be to have the method getOffendingVector() return an Object, and try to cast it to a RealVector or a double[] when catching the exception. Not too sure it's good practice to return Objects, though. I'm looking forward to reading your comments, and will update the sources accordingly. Sebastien --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
