## Tuesday, August 6, 2013

### VirtualLeaf tutorial: Fatal error message stepwise underflow in rkqs, with h=0.000000 and htry = 0.100000

TL;DR: In order to successfully run a model you have to have a suitable geometry for the model to initiate.

When trying to run parts of the VirtualLeaf tutorial, I have been running into the following error when running the simulation.
Fatal error message stepwise underflow in rkqs, with h=0.000000 and htry = 0.100000


Per usual, this turns out to be my lack of understanding on how VirtualLeaf works (baby steps). From my current understanding, one can build models, i.e. mymodel.cpp, and one can run those models on different initial cellular geometries called "leaves", i.e. *.xml files.

It turns out that I was lacking the correct leaf geometry, *.xml file which is defaulted in my header file for the model, i.e. mymodel.h .In order to successfully run a model you have to have a suitable geometry for the model to initiate. I know of how to modify this in two ways:

 virtual QString DefaultLeafML(void) {
return QString("yourfavoriteleafgeometry.xml");
}


You can change yourfavoriteleafgeometry.xml to another *.xml which I found in VirtualLeaf-v1-0.1-src/data/leaves/* . Save file, make, reopen VirtualLeaf and simulate.

2) Or, you can create your leaf geometry, stop simulation, save File -> Save Leaf -> yourfavoriteleafgeometry.xml.

Just make sure that the DefaultLeafML Qstring is the the correct leaf geometry you need for your model!