matrix routine for forming pullback spans
first pass at writing a leibniz routine which is sensitive to partial definitions
some boring fussing with the demo code
whoops, forgot to remove some old code
specify the second differential in the demo SS; successfully compute differentials in the positive range. :)
Merge remote-tracking branch 'origin'
stepping toward getting negative differentials
slightly more efficient production of MultiplicationEntries on tensor
fully correct leibniz application, along with naive redundancy checking to keep invertible class propagation under control. :)