GNU Octave Manual Version 3 by John W. Eaton, David Bateman, Søren Hauberg Paperback (6"x9"), 568 pages ISBN 095461206X RRP £24.95 ($39.95) |
26.6 Miscellaneous Functions
- Function File: poly (a)
- If a is a square N-by-N matrix,
poly (a)
is the row vector of the coefficients ofdet (z * eye (N) - a)
, the characteristic polynomial of a. As an example we can use this to find the eigenvalues of a as the roots ofpoly (a)
.roots(poly(eye(3))) => 1.00000 + 0.00000i => 1.00000 - 0.00000i => 1.00000 + 0.00000i
In real-life examples you should, however, use the
eig
function for computing eigenvalues.If x is a vector,
poly (x)
is a vector of coefficients of the polynomial whose roots are the elements of x. That is, of c is a polynomial, then the elements ofd = roots (poly (c))
are contained in c. The vectors c and d are, however, not equal due to sorting and numerical errors.See also eig, roots
- Function File: polyout (c, x)
- Write formatted polynomial
c(x) = c(1) * x^n + ... + c(n) x + c(n+1)
and return it as a string or write it to the screen (if nargout is zero). x defaults to the string
"s"
.See also polyval, polyvalm, poly, roots, conv, deconv, residue, filter, polyderiv, and polyinteg
- Function File: polyreduce (c)
- Reduces a polynomial coefficient vector to a minimum number of terms by
stripping off any leading zeros.
See also poly, roots, conv, deconv, residue, filter, polyval, polyvalm, polyderiv, polyinteg
ISBN 095461206X | GNU Octave Manual Version 3 | See the print edition |