Without using the roots command, write a function to calculate roots of the quadratic equation

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Chris
Chris on 24 Jun 2013
Without using the roots command, write a function to calculate roots of the quadratic equation
ax^2+bx+c=0
Inputs to the function should be the coefficients a, b and c and output should be the roots. Test your program by setting a=2,b=3,c=-1
can someone help me out with this? I cant think of anything but roots to use. would I have to use poly? or fzero?

Accepted Answer

Evan
Evan on 24 Jun 2013
No need to call any built-in function. Just write your own using the quadratic formula.

More Answers (2)

Tom
Tom on 24 Jun 2013
I'd recommend maths.

James Tursa
James Tursa on 24 Jun 2013
You can use one of the formulations here:
The quadratic formula is listed, of course, but that is prone to cancellation error. So I would advise impressing your professor by coding up the algorithm under the "Avoiding loss of significance" section.
  2 Comments
James Tursa
James Tursa on 25 Jun 2013
It would be best if you could post what you have so far and then we can comment on it and suggest improvements. E.g., a function outline would be this (e.g., put in a file called quadratic_roots.m):
function [x1 x2] = quadratic_roots(a,b,c)
% add your code here to calculate x1 and x2
return
end

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