×
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.

# lsolve with known values

## lsolve with known values

(OP)
Hi,

I am trying to solve a linear system of equations with lsolve but there are certain values of the solution that are known.

How can I do this?

Thanks

### RE: lsolve with known values

Maybe I'm oversimplifying this, but since you seem to be saying that you know one of the coefficients to the system of equations, just specify that as an equality prior to using lsolve to obtain the solution.

rjw57

### RE: lsolve with known values

First thought:

since lsolve is a linear solution to a perfectly conditioned problem then it doesn't matter if you already know one of the answers, it should come out the same again.

Second thought: substitute your known value into the equations and then tidy them up. This will give you a smaller matrix to solve

Cheers

Greg Locock

### RE: lsolve with known values

(OP)
Hi

I should have specified this in my first post.

I want to solve Kx=F for x so

x:=lsolve(K,F)

very simple, but I have restrictions for x, ie. x1=0 and x5=3.5.  How do I specify this?

I have also tried the Given/Find block but it only spits out my initial guesses no matter what they are.

any help would be great.

Thanks

René

#### 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!