On Wed, 2 Jun 2010, ultrokevjr wrote:
< to resolve the following equations under maxima 5.21.1 with wxmaxima as gui:
<
< eq1:(y[i]-y[1])/(y[1]-y[2])=y[1]*(1+K[L]*rho*y[2])/y[2]/(1+K[L]*rho*y[1]);
< eq2:(y[i]-y[1])/(y[2]-y[f])=y[1]*(1+K[L]*rho*y[f])/y[f]/(1+K[L]*rho*y[1]);
< ev(solve([eq1,eq2],[y[1],y[2]]),float,y[i]=0.158,y[f]=0.047,rho=1000,K[L]=0.001294);
<
< wxmaxima just shows `maxima is calculating` after almost ten hours.
<
< while maple 13.02 gives the result almost immediately:
<
< eq1:(y[i]-y[1])/(y[1]-y[2])=y[1]*(1+K[L]*rho*y[2])/y[2]/(1+K[L]*rho*y[1])
< eq2:(y[i]-y[1])/(y[2]-y[f])=y[1]*(1+K[L]*rho*y[f])/y[f]/(1+K[L]*rho*y[1])
< evalf(eval(solve({eq1, eq2}, [y[1], y[2]]), [y[i] = 0.158, y[f] = 0.47, rho = 1000, K[L] = 0.129]))
<
< [[y[1] = 0.1067788429, y[2] = 0.07118961648]]
<
< So, is it possible adjust maxima parameters to faster the calculate, or it's just due to lack of certain optimization?
<
<
I don't find any difficulty in solving this problem:
(%i1) build_info();
Maxima version: 5.21.1
Maxima build date: 20:11 5/9/2010
Host type: i686-pc-linux-gnu
Lisp implementation type: CMU Common Lisp
Lisp implementation version: CVS 19d 19d-release (19D)
(%o1) ""
(%i2)
eq1:(y[i]-y[1])/(y[1]-y[2])=y[1]*(1+K[L]*rho*y[2])/y[2]/(1+K[L]*rho*y[1]);
(%o2) (y[i]-y[1])/(y[1]-y[2]) = y[1]*(y[2]*rho*K[L]+1)
/(y[2]*(y[1]*rho*K[L]+1))
(%i3)
eq2:(y[i]-y[1])/(y[2]-y[f])=y[1]*(1+K[L]*rho*y[f])/y[f]/(1+K[L]*rho*y[1]);
(%o3) (y[i]-y[1])/(y[2]-y[f]) = y[1]*(y[f]*rho*K[L]+1)
/(y[f]*(y[1]*rho*K[L]+1))
(%i4) showtime:true$
Evaluation took 0.0000 seconds (0.0000 elapsed) using 32 bytes.
(%i5)
ev(solve([eq1,eq2],[y[1],y[2]]),float,y[i]=0.158,y[f]=0.047,rho=1000,K[L]=0.001294);
Evaluation took 0.0700 seconds (0.0700 elapsed) using 1.373 MB.
(%o5) [[y[1] = .1067788383756674,y[2] = .07118961595075605],
[y[1] = -.07862590085875154*%i-.06536849090072218,
y[2] = .05715217932542285*%i-.02826732059625807],
[y[1] = .07862590085875155*%i-.06536849090072218,
y[2] = -.05715217932542285*%i-.02826732059625807],
[y[1] = 6.863414634146341,y[2] = -0.380715123094959]]
Could you try doing this computation in either Xmaxima or command-line
Maxima, please.
Leo
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