Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Smath - Given/Find Workaround? 1

Status
Not open for further replies.
Sparweb

Sparweb

Aerospace
Joined
May 21, 2003
Messages
5,181
Location
CA
Still struggling with Smath - features from Mathcad that are not (yet) available.


Can anyone suggest workaround method?

I have a system of 5 unknowns & 5 independent equations, and I would prefer not to bend over backwards or totally hamper the legible calculations to solve it.
Especially when the original calculation in Mathcad needed a single "Find" line to solve it. Life it too short to spend it on algebraic substitutions.

[aside...]
The equations are expressed in a specific to be consistent with an accepted design guide that is commonly used in my industry, and most easily readable to the person reviewing my work. I do not want to turn this into a high school math class, with a page of algebraic substitution.
Yes, there are 7 equations. 2 are not independent. They are shown to clarify the deflection model, per my explanation above.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF
 
Sort by date Sort by votes
Can't get to the SMath stuff at work, but Google points to According to the manual, if you can express the system as a matrix equation, then you can use Invert() as a possible approach, assuming the inverse exists.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
Upvote 0 Downvote
Yes,
But exactly what I'm trying to avoid.
A colleague of mine is working his way through a matrix definition for today's job - but it is a source of many potential errors and misunderstandings when used in the future. Every new joint configuration needs to re-write the matrix anew.


No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF
 
Upvote 0 Downvote
My apologies for pouring out the frustration on you.
Thank you for the suggestion. We will be making do with the matrices.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF
 
Upvote 0 Downvote
Did you try the approach in ? I tried with your example, but it threw a syntax error. When looking at the 5 constraints, there appears to be redundancies q.D == q.D2 + q.a and q.D == q.a + q.b, which means that q.D2=q.b Likewise, q.S is constrained twice. I don't know if that was done for convenience or are typos, but that could make any solution somewhat indeterminate, although solvers should still be able to plow through that.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
Upvote 0 Downvote
Hi,
Thank you for the link. I will experiment with that. Implicit solve looks like the trick, with only a few extra steps to find the solution to an arbitrary system of equations. Hopefully it can cope with non-linear equations too. That would take care of everything.

You're right to point out the redundancies, but allow me to clarify what I referred to in the "aside" of the OP. The equations are written in full to illustrate all combinations of geometric relationships between the variables. These variables all relate to the geometry of a joint between two pieces of sheet-metal, with rows of fasteners. My report will be reviewed and approved by an outside agency, who has access to the same book I am referring to for this procedure. The original book reports all combinations of geometric relationship. If I omit the ones that are not independent, I will be technically correct, but risk the reviewer considering my work incomplete. Some people like to see the lines in the textbook parroted back to them. I don't know if this reviewer thinks that way, but best not to risk it.


No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

wb.c
  • Locked
  • Question Question
SMath Down?
Replies
1
Views
953
IRstuff
IRstuff
dik
  • Locked
  • Question Question
SMath Integer
Replies
2
Views
416
dik
dik
Sparweb
  • Locked
  • Question Question
SMath version rollback
Replies
5
Views
2K
Sparweb
Sparweb
francis_intano
  • Locked
  • Question Question
SMath Advanced and Enterprise Users
Replies
0
Views
833
francis_intano
francis_intano
dik
  • Locked
  • Question Question
SMath Problem
2
Replies
21
Views
1K
dik
dik

Part and Inventory Search

Sponsor

Back
Top