+ if ((sol_x != x) ||
+ (sol_y != t)) {
+ ++result;
+ clog << "solution of the system " << eqns << " for " << vars
+ << " erroneously returned " << sol << endl;
+ }
+
+ return result;
+}
+
+static unsigned exam_lsolve3S(void)
+{
+ // A degenerate example that went wrong while trying to improve elimination
+ unsigned result = 0;
+ symbol b("b"), c("c");
+ symbol x("x"), y("y"), z("z");
+ lst eqns, vars;
+ ex sol;
+
+ // Create the linear system [y+z==b,-y+z==c] with one additional row...
+ eqns.append(ex(0)==ex(0)).append(b==z+y).append(c==z-y);
+ // ...to be solved for [x,y,z]...
+ vars.append(x).append(y).append(z);
+ // ...and solve it:
+ sol = lsolve(eqns, vars);
+ ex sol_x = sol.op(0).rhs(); // rhs of solution for first variable (x)
+ ex sol_y = sol.op(1).rhs(); // rhs of solution for second variable (y)
+ ex sol_z = sol.op(2).rhs(); // rhs of solution for third variable (z)
+
+ // It should have returned [x==x,y==t,]
+ if ((sol_x != x) ||
+ (sol_y != (b-c)/2) ||
+ (sol_z != (b+c)/2)) {