How to find only positive root of a polynomial
16 visualizaciones (últimos 30 días)
Mostrar comentarios más antiguos
How to find only positive root of a polynomial equation x^4+7*x^2-A=0 where A is varying from 1:.1:3. If rr is the positive real root, then find rr/(rr+1) for each case.
for A=1:.1:3
poly = [1 0 7 0 A];
R = roots(poly);
if isa(R,'complex') && (R<=0)
continue;
else
R/(R+1)
end
Please correct the code.
2 comentarios
Matt J
el 16 de Abr. de 2013
What do you mean by "without solving a polynomial equation"? A root is, by definition, the solution to such a problem.
Respuesta aceptada
Matt J
el 16 de Abr. de 2013
Editada: Matt J
el 16 de Abr. de 2013
By the quadratic formula, the largest solution for x^2 is
x^2 = (-7+ sqrt(49+4*A))/2
For positive A, this will always be positive. You can then get a positive root for x by doing
x = sqrt( (-7+ sqrt(49+4*A))/2 )
I don't know if this satisfies your requirement "without solving a polynomial equation". It doesn't seem possible that you meant this literally (see my comment above).
Más respuestas (0)
Ver también
Categorías
Más información sobre Operating on Diagonal Matrices en Help Center y File Exchange.
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!