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roots

Polynomial Roots

roots(p)

  • It returns the roots of the following polynomial: $$ p_nx^n+p_{n-1}x^{n-1}+\cdots+p_1x+p_0. $$
  • p is a vector containing the coefficents, where p(1) corresponds to the highest order term.
  • p should be non-empty and should not contain inf and nan.
  • If p is a logical or character array, it will be converted to a double array before executing poly(a).

Example 1: Roots of a polynomial of order 6. Complex roots are shown in conjugate pairs.

roots([0.5 0.5 1 2 3 7 8])
ans =
  1.138 + 1.345i
  1.138 - 1.345i
 -0.335 + 1.605i
 -0.335 - 1.605i
 -1.303 + 0.469i
 -1.303 - 0.469i

Example 2: Polynomial coefficients can be complex. In this case, the roots are not necessarily conjugate pairs.

roots([0 0 1+i 2 3+0.5i])
ans =
 -0.223 + 1.852i
 -0.777 - 0.852i