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Find() gives solution outside the constraints

SOLVED

Re: Find() gives solution outside the constraints

Also, comparing complex number with integer does not make sense.

How about if I change the constraint in the original setup to

Fmin <= Re(Fx) <=2.

This would make sense, but I still do not get the correct answer.

Re: Find() gives solution outside the constraints

Looks like Mathcads symbolic is running into some bad kind of numeric roundoff errors, even in "exact" mode.

Solving in exact mode (by avoiding any decimal point) Mathcad delivers complex solutions (as shown in the sheet I posted above) no matter if I solve the original equation or the Alan's modification.

If we sqare those solutions we get some positive real numbers, though!

Also by looking at the graph we should expect real solutions.

See at the end of the attached sheet

Highlighted

Re: Find() gives solution outside the constraints

Is there any convenient way in MathCAD to filter the numbers outside of the specified range from the vector?

Fx_real=(-0.344 0.344 -1.056, 1.056)

and the constraint is still Fmin<Fx_real<2

Re: Find() gives solution outside the constraints

Is there any reason you must use the symbolic solver? Numerically, you get what you want right away:

Fxsolveb.PNG

Alan

View solution in original post

Re: Find() gives solution outside the constraints

No particular reason, and thank you! I think this is the problem I was having.

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