Verifying Solution for PDF to CDF and Inverse CDF Calculations

  • Thread starter Thread starter zzmanzz
  • Start date Start date
  • Tags Tags
    Cdf Inverse Pdf
Click For Summary

Homework Help Overview

The discussion revolves around verifying calculations related to probability density functions (PDF), cumulative distribution functions (CDF), and their inverses. The original poster presents a piecewise-defined PDF and seeks confirmation of their derived CDF and inverse CDF.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants examine the correctness of the inverse CDF, particularly questioning the choice of root in the interval from 0.5 to 1. There is a focus on ensuring that the values remain within the expected range.

Discussion Status

The discussion is ongoing, with participants actively engaging in identifying potential errors in the original poster's calculations. There is a recognition of the need to reassess the chosen root for the inverse CDF, but no consensus has been reached yet.

Contextual Notes

Participants are considering the implications of the chosen root on the validity of the inverse CDF, particularly regarding its range and adherence to the properties of cumulative distribution functions.

zzmanzz
Messages
47
Reaction score
0

Homework Statement



I was hoping someone could just verify this solution is accurate.

p(x) =
0 , x < 0
4x, x < .5
-4x + 4 , .5 <= x < 1

Find CDF and Inverse of the CDF.

Homework Equations

The Attempt at a Solution



CDF =
0 , x < 0
2x^2 , 0 <= x < .5
-2x^2 + 4x - 1 , .5 <= x <= 1
1, x > 1

Inverse of the CDF

0 , x < 0
sqrt( x / 2) , 0 <= x < .5
1 + sqrt ( 1 - x) / sqrt ( 2 ) , .5 <= x <= 1
1, x > 1


Thanks[/B]
 
Physics news on Phys.org
zzmanzz said:

Homework Statement



I was hoping someone could just verify this solution is accurate.

p(x) =
0 , x < 0
4x, x < .5
-4x + 4 , .5 <= x < 1

Find CDF and Inverse of the CDF.

Homework Equations

The Attempt at a Solution



CDF =
0 , x < 0
2x^2 , 0 <= x < .5
-2x^2 + 4x - 1 , .5 <= x <= 1
1, x > 1

Inverse of the CDF

0 , x < 0
sqrt( x / 2) , 0 <= x < .5
1 + sqrt ( 1 - x) / sqrt ( 2 ) , .5 <= x <= 1
1, x > 1


Thanks[/B]
You chose the wrong root for ##.5 \leq x \leq 1##. Can you see why?
 
Ray Vickson said:
You chose the wrong root for ##.5 \leq x \leq 1##. Can you see why?

Thanks for pointing that out. The value for that should also be between .5 and 1, and with that root, it can be greater than 1?
 
zzmanzz said:
Thanks for pointing that out. The value for that should also be between .5 and 1, and with that root, it can be greater than 1?

Yes, just look at it: you have ##1 + \text{something positive}##.
 
Ray Vickson said:
Yes, just look at it: you have ##1 + \text{something positive}##.
Thank you!
 

Similar threads

Replies
4
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 3 ·
Replies
3
Views
5K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 14 ·
Replies
14
Views
1K
Replies
4
Views
10K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 8 ·
Replies
8
Views
12K
  • · Replies 105 ·
4
Replies
105
Views
8K