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Find issue

ejanssen
1-Newbie

Find issue

Hi,

I'm new at mathcad so maybe this is a basic issue.

I'm trying to solve this equation with find command, but i get a green box and no answer.

2016-05-06_15-43-15.png

9 REPLIES 9
MJG
18-Opal
18-Opal
(To:ejanssen)

The green box indicates that Mathcad is trying to calculate.

When trying to solve symbolically (as you show), I also get the green box while Mathcad tries to find the solution.  I did not wait long enough for it to finish.  You can try letting it run in the background to see if it ever finishes.

Do you need a symbolic solution, or would a numerical solution work?  When I try to solve numerically with d=0 as the guess value, I get an undefined error.  However, when I change the guess to 0.00001, I get the following:

LucMeekes
23-Emerald III
(To:ejanssen)

Your sking for a symbolic solution, but with the powers of d that's not going to work.

Problem is numerically solvable, using the root function.

(If 'difficult expression'=m, then 'difficult expression' - m must be zero, that's what the root function will search.)

Now the result is complex, did you expect that?

Success!
Luc

A real solution is found for smaller guess values.

LucMeekes
23-Emerald III
(To:MJG)

I find no real solution.

Interesting.  In using the Root method, I was able to get this solution only by a very close guess value:

using any fewer significant digits in my guess value resulted in a complex solution.

LucMeekes
23-Emerald III
(To:MJG)

It is interesting. Especially to see that there's only a very narrow range where real solutions to the problem exist.

LucMeekes
23-Emerald III
(To:LucMeekes)

To check that the result is OK, feed it back:

Check!

Hi LucMeekes & Mark Gase,

Thanks for your reply ! I'm searching for a real solution, the value that i get should be the diameter of a critical orifice (for in-compressible flow).

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