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

If Statment with

If Statment with

If Statment with


I am new to Mathcad and a bit confused. I am trying to use an if statement to say something like the following:


Lr(R,gamma,theta):=if(phi(R,gamma,theta)< theta, 2, 10)



phi(R,gamma,theta):= atan(hr/Lg(theta))
Lg(theta):= Ls(theta)*cos(theta)
Ls(theta):= 2*hr/sin(theta)

However it wont work when i try to output the value of


, I am getting a "must be real" error. If i change the boolean statement in the if statement to


phi(R,gamma,theta)= theta
it outputs an answer fine, however this is not what i need to work out! Does anyone know why this is?

Thanks in advance

RE: If Statment with

What values or R, gamma, theta are you using?


RE: If Statment with

I'm not sure what I've done but it seems to work now! The values of R, gamma and theta vary but in my examples that didnt work R was about 15, gamma was 90 and theta about 0.2. I've been playing around a bit with the algorithms and think I may have been using a variable in the right-hand part of the declaration that I hadn't put as an arguement in the left-hand part, but as this variable was declared at some point above this then it wasn't being picked up as not declared. It may have had an inappropriate value in from another calulation which was causing this. I am not sure though.

Thanks for you reply

RE: If Statment with

Bear in mind that the default unit for trig functions in Mathcad is the radian, not degree.


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