I have updated the LinSolve snippet in the gallery. Now there is a function Residual() for checking solutions of systems of equations.
It does not require the solution to be assigned to the variables, just specify the system and the solution vector. The vector can be generated in place by
the call to the solver.
This way you can test and document the solution quality without lots of assignments and Clear() calls or switching on and off alternatives.

Martin Kraska
Pre-configured portable distribution of SMath Studio: https://en.smath.info/wiki/SMath%20with%20Plugins.ashx