<Goal Seek seems to permit far less user control

I don't think so. Goal Seek takes its parameters from the Iteration dialog: the max number of "iterations" and the maximum change,
which can be set to what Harlan called "machine precision".

Not that I want to restart the discussion about how desirable such a solution is, just to indicate that accuracy should not be an
issue.

--
Kind regards,

Niek Otten
Microsoft MVP - Excel


"Jerry W. Lewis" wrote in message ...
| Solver's default settings greatly limit its accuracy, but I can usually tweak
| it to get what I want. Goal Seek seems to permit far less user control.
| However, I suspect that most algorithms would perform poorly when asked to
| numerically solve an n-dimensional problem that analytically reduces to an
| n-k (k0) dimensional problem. Do the analytical reduction as Harlan
| suggested, then apply appropriate methods to the problem that remains.
|
| If the algebra is tedious, download Maxima
| http://maxima.sourceforge.net
| which is a free symbolic math program. In Maxima,
| solve ([21*x+ 6*y = 10, (7*x-20)^2+(6*y+10)^2=200], [x,y]);
| returns the two solutions to the reduced quadratic equation
| [x=10/7,y=-10/3],[x=6/7,y=-4/3]
| With more complicated equations, you might get a reduction that actually
| requires a numerical solution, but with a clear picture of the actual
| dimensionality of the problem, Solver will perform much better.
|
| Jerry
|
| "David A. Heiser" wrote:
|
| Using Solver to solve these equation sets is a disaster. You cannot rely on
| the accuracy of the results, which generally are only accurate to 2-3
| decimal digits. Most of the time it is not accurate to any decimal digit.
| The algorithm is faulty.
|
| David Heiser