×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• 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.

# Solving system of ODE using rkfixed

## Solving system of ODE using rkfixed

(OP)
I have a system of ODE. There are 6 unknowns (4 second derivative, and 2 first derivative), and 6 equations.

In each differential equation, that particular unknwon is a function of 5 other unknowns, all to their highest order of derivatives.

My experience on MATHCAD is limited, but based on what I know, this creates a very problematic situation. When I tried to construct the D(t,X) function, I am really having tough time rearranging each differential equation such that the highest derivative of the remaining 5 unknowns do not appear in each differential equation. I don't think I can ever achive that goal. Each differential equation is so complex that the MATHCAD (version 2001) can't even show the complete symbolic term because it is way too large.

So my problem is like this: having such a system of ODE, where each differential equation is a function of the remaining unknowns to their highest derivative, how would I construct the D(t,X) function?

### RE: Solving system of ODE using rkfixed

You might want to search the Mathcad collaboratory website and/or post your question there.  There have been several postings on using RKFIXED there:

TTFN

#### 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.

#### Resources

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
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™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:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!