Mathcad's numerical solvers make use of two tolerance
parameters in calculating solutions in solve blocks: CTOL and TOL.
If your system does not converge, and you would like to know the solution
that was found, even though it did not meet the convergence criteria,
use Minerr.
Getting Past Errors
If the solver cannot make any further improvements to the solution,
but the constraints are not all satisfied, the solver stops and marks
Find with an error message. This happens whenever the difference between
successive approximations to the solution is greater than TOL and:
The solver cannot reduce the error any further.
The solver reaches a point where it has no basis
on which to make further iterations.
The solver reaches the limit of its accuracy. Round-off
errors make it unlikely that further computation would increase accuracy
of the solution. This often happens if you set TOL to a value below 10
-15.
The following problems may cause this kind of failure:
There may be no solution.
You may have given real guesses for an equation with
no real solution. If the solution for a variable is complex, the solver
will not find it unless the starting value for that variable is also complex.
The solver may have become trapped in a local minimum
for the error values. To find the actual solution, try using different
starting values or add an inequality to keep Mathcad from being trapped
in the local minimum.
The solver may have become trapped on a point from
which it cannot determine where to go next. Again, try changing the initial
guesses or adding an inequality to avoid the undesirable stopping point.
If you can not solve the constraints to within the desired tolerance,
try defining TOL with a larger value somewhere above the solve block.
Increasing the tolerance changes what Mathcad considers close enough to
call a solution.