currentVector.assign(otherVector, minus) takes the other vector, and subtracts it from currentVector, which mutates currentVector. If currentVector is DenseVector, this is already optimized. It could be optimized if currentVector is RandomAccessSparse.
-jake On Thu, Feb 18, 2010 at 1:29 PM, Robin Anil <robin.a...@gmail.com> wrote: > Just to be clear, this does: > currentVector-otherVector ? > > currentVector.assign(otherVector, Functions.minus); > > > > On Fri, Feb 19, 2010 at 2:57 AM, Jake Mannix <jake.man...@gmail.com> > wrote: > > > to do subtractFrom, you can instead just do > > > > Vector.assign(otherVector, Functions.minus); > > > > The problem is that while DenseVector has an optimization here: if the > > BinaryFunction passed in is additive (it's an instance of PlusMult), > > sparse iteration over "otherVector" is executed, applying the binary > > function and mutating self. AbstractVector should have this optimization > > in general, as it would be useful in RandomAccessSparseVector (although > > not terribly useful in SequentialAccessSparseVector, but still better > than > > current). > > > > -jake > > > > On Thu, Feb 18, 2010 at 1:19 PM, Robin Anil <robin.a...@gmail.com> > wrote: > > > > > I just had to change it at one place(and the tests pass, which is > scary). > > > Canopy is really fast now :). Still could be pushed > > > Now the bottleneck is minus > > > > > > maybe a subtractFrom on the lines of addTo? or a mutable negate > function > > > for > > > vector, before adding to > > > > > > Robin > > > > > > > > > > > > On Fri, Feb 19, 2010 at 2:43 AM, Jake Mannix <jake.man...@gmail.com> > > > wrote: > > > > > > > I use it (addTo) in decomposer, for exactly this performance issue. > > > > Changing > > > > plus into addTo requires care, because since plus() leaves arguments > > > > immutable, > > > > there may be code which *assumes* that this is the case, and doing > > > addTo() > > > > leaves side effects which might not be expected. This bit me hard on > > svd > > > > migration, because I had other assumptions about mutability in there. > > > > > > > > -jake > > > > > > > > On Thu, Feb 18, 2010 at 1:09 PM, Robin Anil <robin.a...@gmail.com> > > > wrote: > > > > > > > > > ah! Its not being used anywhere :). Should we make that a big task > > > before > > > > > 0.3 ? Sweep through code(mainly clustering) and change all these > > > things. > > > > > > > > > > Robin > > > > > > > > > > > > > > > > > > > > On Fri, Feb 19, 2010 at 2:36 AM, Sean Owen <sro...@gmail.com> > wrote: > > > > > > > > > > > Isn't this basically what assign() is for? > > > > > > > > > > > > On Thu, Feb 18, 2010 at 9:04 PM, Robin Anil < > robin.a...@gmail.com> > > > > > wrote: > > > > > > > Now the big perf bottle neck is immutability > > > > > > > > > > > > > > Say for plus its doing vector.clone() before doing anything > else. > > > > > > > There should be both immutable and mutable plus functions > > > > > > > > > > > > > > > > > > > > > > > > > > > >
