Home > Numerical methods > Roots of Non-Linear Equation > Fixed Point Iteration method example

4. Fixed Point Iteration method example ( Enter your problem )
  1. Algorithm & Example-1 `f(x)=x^3-x-1`
  2. Example-2 `f(x)=2x^3-2x-5`
  3. Example-3 `x=sqrt(12)`
  4. Example-4 `x=root(3)(48)`
  5. Example-5 `f(x)=x^3+2x^2+x-1`

1. Algorithm & Example-1 `f(x)=x^3-x-1`





Algorithm
Fixed Point Iteration method Steps (Rule)
Step-1: First write the equation `x = phi(x)`
Step-2: Find points `a` and `b` such that `a < b` and `f(a) * f(b) < 0`.
Step-3: If `f(a)` is more closer to 0 then `f(b)`
then `x_0=a` else `x_0=b`
Step-4: `x_1 = phi(x_0)`
`x_2 = phi(x_1)`
`x_3 = phi(x_2)`
...
Repeat until `|f(x_i)-f(x_(i-1))| ~~ 0`

Example-1
1. Find a root of an equation `f(x)=x^3-x-1` using Fixed Point Iteration method

Solution:
Method-1
Let `f(x) = x^3-x-1`

Here `x^3-x-1=0`

`:.x^3=x+1`

`:.x=root (3)(x+1)`

`:.phi(x)=root (3)(x+1)`

Here
`x`012
`f(x)`-1-15



Here `f(1) = -1 < 0` and `f(2) = 5 > 0`

`:.` Root lies between `1` and `2`

`x_0 = (1 + 2)/2 = 1.5`


`x_1 = phi(x_0) = phi(1.5) = 1.35721`

`x_2 = phi(x_1) = phi(1.35721) = 1.33086`

`x_3 = phi(x_2) = phi(1.33086) = 1.32588`

`x_4 = phi(x_3) = phi(1.32588) = 1.32494`

`x_5 = phi(x_4) = phi(1.32494) = 1.32476`


Approximate root of the equation `x^3-x-1` using Iteration method is `1.32476` (After 5 iterations)

`n``x_0``x_1=phi(x_0)`UpdateDifference
`|x_1-x_0|`
21.51.35721`x_0 = x_1`0.14279
31.357211.33086`x_0 = x_1`0.02635
41.330861.32588`x_0 = x_1`0.00498
51.325881.32494`x_0 = x_1`0.00094
61.324941.32476`x_0 = x_1`0.00018





This material is intended as a summary. Use your textbook for detail explanation.
Any bug, improvement, feedback then Submit Here





Share this solution or page with your friends.
 
 
Copyright © 2026. All rights reserved. Terms, Privacy
 
 

.