Very productive day. My client uses some engineering analysis software (combustion related stuff) and in certain situations it was giving them something other than what they expected. It turns out that the highly non-linear problem that they are solving has multiple solutions for certain boundary conditions. The solution algorithm would sometimes converge to a solution that they were not interested in. I figured out how it make it converge to the solution that they want. I am not getting paid (as of yet) to rewrite the code to do what they want. For this part of the task I am just supposed to "exercise" the code to demonstrate when it gives good results and when it is "lacking". I did do some "quick and dirty" code changes to get the "right" solutions outside of the parameter space that worked with the unmodified code and explained how/why it works. They are getting a bargain.