Will solve the equation system [A][X]=[B] where:
[aBody][this]=[this] is [A][X]=[B] ("this" is the right hand
side, and it will be overwritten with the solution).
[A] is upper/right triangular
Will solve the equation system [A][X]=[B] where:
[aBody][this]=[this] is [A][X]=[B] ("this" is the right hand
side, and it will be overwritten with the solution).
[A] is lower/left triangular