48/50 Linear System Solver

[Marcus von Cube]

(02-16-2014 06:00 PM)Dieter Wrote:  The system is exactly determined (three variables in three equations), but its determinant is zero.

If I try to solve the system manually I get 0 = 5 which is obviously false irrespective of the values of x, y or z. So the system has no solution. A determinant of zero can say "no solution" or "a linear set of solutions" (depending on the right hand side) but it certainly does not say "exactly one solution".

Any calculator should error out on this equation. If I understand the excerpt from the 48G manual correctly, the result of LINSOLV occasionally is a least squares approximation. This is OK if the coefficients come from real world data and a solution is expected to exist but does not because of limited accuracy of the input.