28.6 Miscellaneous Functions

poly (A)

poly (가로)

If A is a square N-by-N matrix, poly (A) is the row vector of the coefficients of det (z * eye (N) - A), the characteristic polynomial of A.

For example, the following code finds the eigenvalues of A which are the roots of poly (A).

roots (poly (eye (3)))
    ⇒ 1.00001 + 0.00001i
       1.00001 - 0.00001i
       0.99999 + 0.00000i

In fact, all three eigenvalues are exactly 1 which emphasizes that for numerical performance the eig function should be used to compute eigenvalues.

If 가로 is a vector, poly (가로) is a vector of the coefficients of the polynomial whose roots are the elements of 가로. That is, if c is a polynomial, then the elements of d = roots (poly (c)) are contained in c. The vectors c and d are not identical, however, due to sorting and numerical errors.

같이 보기: roots, eig.

polyout (c)

polyout (c, 가로)

문자열 = polyout (…)

Display a formatted version of the polynomial c.

The formatted polynomial

c(x) = c(1) * x^n + … + c(n) x + c(n+1)

is returned as a string or written to the screen if nargout is zero.

The second argument 가로 specifies the variable name to use for each term and defaults to the string "s".

같이 보기: polyreduce.

polyreduce (c)

Reduce a polynomial coefficient vector to a minimum number of terms by stripping off any leading zeros.

같이 보기: polyout.