Why is numden function returning values with fractions?
2 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
I'm trying to simplify an expression. I wrote:
>> syms r a b c d x y;
A = tanh(a/4)*sqrt((cosh(r)-cosh(a/2))/(cosh(r)+cosh(a/2)));
B = tanh(b/4)*sqrt((cosh(r)-cosh(b/2))/(cosh(r)+cosh(b/2)));
C = tanh(c/4)*sqrt((cosh(r)-cosh(c/2))/(cosh(r)+cosh(c/2)));
D = tanh(d/4)*sqrt((cosh(r)-cosh(d/2))/(cosh(r)+cosh(d/2)));
sigma1 = A + B + C + D;
sigma2 = A*B + A*C + A*D + B*C + B*D + C*D;
sigma3 = A*B*C + A*B*D + A*C*D + B*C*D;
sigma4 = A*B*C*D;
tA4_1 = (sigma1 - sigma3) / (1 + sigma4 - sigma2);
tA4_2 = subs(tA4_1, cosh(r), x/y);
[n1, d1] = numden(expand(tA4_2))
The result that I got was
n1 =
tanh(a/4)*tanh(b/4)*tanh(c/4)*((x - y*cosh(a/2))/(x + y*cosh(a/2)))^(1/2)*((x - y*cosh(b/2))/(x + y*cosh(b/2)))^(1/2)*((x - y*cosh(c/2))/(x + y*cosh(c/2)))^(1/2) - tanh(b/4)*((x - y*cosh(b/2))/(x + y*cosh(b/2)))^(1/2) - tanh(c/4)*((x - y*cosh(c/2))/(x + y*cosh(c/2)))^(1/2) - tanh(d/4)*((x - y*cosh(d/2))/(x + y*cosh(d/2)))^(1/2) - tanh(a/4)*((x - y*cosh(a/2))/(x + y*cosh(a/2)))^(1/2) + tanh(a/4)*tanh(b/4)*tanh(d/4)*((x - y*cosh(a/2))/(x + y*cosh(a/2)))^(1/2)*((x - y*cosh(b/2))/(x + y*cosh(b/2)))^(1/2)*((x - y*cosh(d/2))/(x + y*cosh(d/2)))^(1/2) + tanh(a/4)*tanh(c/4)*tanh(d/4)*((x - y*cosh(a/2))/(x + y*cosh(a/2)))^(1/2)*((x - y*cosh(c/2))/(x + y*cosh(c/2)))^(1/2)*((x - y*cosh(d/2))/(x + y*cosh(d/2)))^(1/2) + tanh(b/4)*tanh(c/4)*tanh(d/4)*((x - y*cosh(b/2))/(x + y*cosh(b/2)))^(1/2)*((x - y*cosh(c/2))/(x + y*cosh(c/2)))^(1/2)*((x - y*cosh(d/2))/(x + y*cosh(d/2)))^(1/2)
d1 =
tanh(a/4)*tanh(b/4)*((x - y*cosh(a/2))/(x + y*cosh(a/2)))^(1/2)*((x - y*cosh(b/2))/(x + y*cosh(b/2)))^(1/2) + tanh(a/4)*tanh(c/4)*((x - y*cosh(a/2))/(x + y*cosh(a/2)))^(1/2)*((x - y*cosh(c/2))/(x + y*cosh(c/2)))^(1/2) + tanh(a/4)*tanh(d/4)*((x - y*cosh(a/2))/(x + y*cosh(a/2)))^(1/2)*((x - y*cosh(d/2))/(x + y*cosh(d/2)))^(1/2) + tanh(b/4)*tanh(c/4)*((x - y*cosh(b/2))/(x + y*cosh(b/2)))^(1/2)*((x - y*cosh(c/2))/(x + y*cosh(c/2)))^(1/2) + tanh(b/4)*tanh(d/4)*((x - y*cosh(b/2))/(x + y*cosh(b/2)))^(1/2)*((x - y*cosh(d/2))/(x + y*cosh(d/2)))^(1/2) + tanh(c/4)*tanh(d/4)*((x - y*cosh(c/2))/(x + y*cosh(c/2)))^(1/2)*((x - y*cosh(d/2))/(x + y*cosh(d/2)))^(1/2) - tanh(a/4)*tanh(b/4)*tanh(c/4)*tanh(d/4)*((x - y*cosh(a/2))/(x + y*cosh(a/2)))^(1/2)*((x - y*cosh(b/2))/(x + y*cosh(b/2)))^(1/2)*((x - y*cosh(c/2))/(x + y*cosh(c/2)))^(1/2)*((x - y*cosh(d/2))/(x + y*cosh(d/2)))^(1/2) - 1
This still contains fractions in the numerator and the denominator, but my impression was that numden was supposed to give the numerator and denominator of a simplified fraction. Did I do something wrong, or is the numden commnand not designed to do this?
Thanks.
0 commentaires
Réponses (0)
Voir également
Catégories
En savoir plus sur Number Theory dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!