Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

genfit Won't Converge

genfit Won't Converge

genfit Won't Converge

Is there any way to get more information out of Mathcad (I'm running version 11) beyond the all red equation with the hover-over message "Can't converge to a solution"?

I was running genfit and I think I have the syntax right after all these years of using it.  I've changed my guess values all over the map with no change.

I tried the MathCad Collaboratory, but I can't find a place in there for this basic a question.


RE: genfit Won't Converge

Try it again.  Do a search in the Collab for:

genfit easy


RE: genfit Won't Converge

OK, I spent the day in the Collab reading.  Seems like the main problem being solved is finding automated ways to generate the vector of derivitives.  Lot of discussion about one of the easiest parts of this process.

What I get is "Can't converge to a solution" and I'm looking for a way to make MathCad give me more information.  I've set the convergence tolerance to 1.0 (the max).  I've picked my guess values at +/- infinity and most values in between.  

One of many things that I don't understand is that the function turns red instantly after I change something.  When genfit works on a dataset of any size it always takes a moment to decide if it wants to answer your question.  With this it is instant.  If I try linfit, pwrfit, expfit or lnfit it doesn't come close to matching the data, but it takes 3-5 seconds to decide on the constants.  With genfit it is immediate.

Any ideas on how to get it to go down a different road to try to converge?


RE: genfit Won't Converge


RE: genfit Won't Converge

I'm trying to solve for five constants.  Excel just runs out of gas.  I finally pulled my head out and took the time to understand the "Easy Genfit" thread on the Collab and it works wonderfully.


RE: genfit Won't Converge

TK Solver Premium has an optimizer in it that is the latest version of solver> Newer and more robust than what is in excel

RE: genfit Won't Converge

Cool, the version of TK I have is 10 years old and anything but robust.  If I find anything that MathCad v11 won't handle I'll look into it.


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close