Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Quick Mathematica Question

Tags:
  1. Oct 3, 2014 #1
    I have equation of motion that our instructor wants to replace one or both of the masses with a negative mass in Mathematica. I tried m1=-m1, but I get an infinite recursion. What is the best way to do this? The equations of motion is a monster, so I don't really want to do this by hand.

    Thanks,
    Chris
     
  2. jcsd
  3. Oct 3, 2014 #2

    OldEngr63

    User Avatar
    Gold Member

    Just a thought: Replace m1 by mm1 or some such, then replace mm1 by - m1. This may allow you to fool the computer.
     
  4. Oct 3, 2014 #3
    Yes, I ended up doing something just like that ##m_1=-m_{11}##.

    Thanks,
    Chris
     
  5. Oct 4, 2014 #4

    Dale

    Staff: Mentor

    The easiest way is:
    eq /.{m1 -> -m1}

    This goes through the expression eq and replaces every occurrence of m1 with -m1. It is very worthwhile learning this technique of using replacement rules.
     
  6. Oct 4, 2014 #5
    Awesome, thank you.

    Chris
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Quick Mathematica Question
  1. Mathematica question (Replies: 10)

  2. Mathematica question (Replies: 1)

  3. Mathematica question (Replies: 4)

Loading...