Problem 1954. Write a cubic formula function

Created by Tyler

Difficulty:Rate

Solve Later
Add To GroupÃ‚

Create a function that will output the three roots of a cubic equation specified by the 4 coefficients listed as input. The output should be sorted using the "sort" function of matlab, to be consistent. Also, the output need only be accurate to the 4th decimal place, and the input "A" will always be non-zero and real.

Example:

A*x^3+B*x^2+C*x+D=0 --> [A,B,C,D]

x^3-6x^2+11x-6=0 --> [1,-6,11,-6]

cubicFormula([1,-6,11,-6]) --> [1,2,3]

Solve

Solution Stats

203 Solutions
19 Solvers

Last Solution submitted on Jan 12, 2024

Last 200 Solutions

Problem Comments

3 Comments

3 Comments

Alfonso Nieto-Castanon on 22 Oct 2013

the "sorted" requirement is problematic, I would suggest you drop this requirement and simply resort the output of cubicFormula after (not before) rounding to four digits (and apply the same logic to your testsuite)...

J.R.! Menzinger on 29 Oct 2013

is there maybe a several problem with the sorting method you describe/need?? :-/

Rafael S.T. Vieira on 5 Sep 2020

The problem requires abs as 'ComparisonMethod' for sorting and the non-conjugate transpose. That's a pain that I have just become aware: ' is the conjugate transpose, and .' is the non-conjugate transpose. The conjugate operator changes the signs of complex roots.

Solution Comments

Show comments

Problem Recent Solvers19

Problem Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Problem 1954. Write a cubic formula function

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers19

Suggested Problems

More from this Author1

Problem Tags

Community Treasure Hunt

Problem 1954. Write a cubic formula function

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers19

Suggested Problems

More from this Author1

Problem Tags

Community Treasure Hunt

Players