Mathematica Stack Exchange is a question and answer site for users of Mathematica. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Limit[expr,x->Subscript[x, 0],Direction->1] computes the limit as x approaches Subscript[x, 0] from smaller values. Limit[expr,x->Subscript[x, 0],Direction->-1] computes the limit as x approaches Subscript[x, 0] from larger values.

This to me is confusing, I though x->4- that x are approaching xo from smaller values, in other words from the left hand side. Why would one therefore use 1 for left hand side and -1 for right hand side. Do not see the logic

share|improve this question
    
Approaching direction corresponds to the direction of axis for example. – Kuba Jul 9 '14 at 8:02
5  
Think of it as the direction you're going, not the direction you're coming from. (Although I do agree with you that it is a little inconsistent with the traditional mathematical notation. Perhaps they should have just used Above and Below for no chance of confusion.) – Rahul Jul 9 '14 at 9:19
up vote 4 down vote accepted

Think of it as the direction you're going, not the direction you're coming from. (Although I do agree with you that it is a little inconsistent with the traditional mathematical notation. Perhaps they should have just used Above and Below for no chance of confusion.)

share|improve this answer
5  
"Above" and "Below" would be problematic when discussing unreal (surreal?) approaches in the complex plane. – Daniel Lichtblau Dec 17 '15 at 22:11

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.