Turn on thread page Beta
    • Thread Starter
    Offline

    16
    ReputationRep:
    or maybe, 'looking for a curve'

    Basically im modelling some situation and I need a curve which is asymptotic to y = 1 as x < ~A and asymptotic to y = 0 as x becomes larger.

    Anyone have any ideas?

    Obviously its not Ae^(-kx) but I think it would involve exponentials...

    Thanks so much

    For what its worth ill rep you if you find an equation which works

    Name:  Screen Shot 2013-03-18 at 07.41.26.png
Views: 85
Size:  19.6 KB
    • Study Helper
    Offline

    15
    Study Helper
    (Original post by 7589200)
    ...
    Does it need to reach 1 as x-->0, or to -infinity? Graph is confusing.

    If it's -infinity:
    An inverse tan would be a good starting point; a few transformations and it will meet your criteria.
    • Thread Starter
    Offline

    16
    ReputationRep:
    (Original post by ghostwalker)
    Does it need to reach 1 as x-->0, or to -infinity? Graph is confusing.

    If it's -infinity:
    An inverse tan would be a good starting point; a few transformations and it will meet your criteria.
    Nah it needs to be close to 1, not reach it, as x=0.

    so 1 as it heads to minus infinity and 0 as it heads to positive infinity
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by 7589200)
    Nah it needs to be close to 1, not reach it, as x=0.

    so 1 as it heads to minus infinity and 0 as it heads to positive infinity
    What about something like y=0.5(1-\tanh(x-k)) ?
    • Thread Starter
    Offline

    16
    ReputationRep:
    (Original post by Mr M)
    What about something like y=0.5(1-\tanh(x-k)) ?
    With k = 2 that's pretty much exactly what I wanted

    thanks very much!
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: March 19, 2013
Poll
Do you think parents should charge rent?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.