eqs:
[ v^2 - 2*v + u^2 + 10*u + 1,
v^2 - 10*v + u^2 + 2*u + 1 ]
solve(eqs,[u,v]) => []
But in fact eqs is solvable:
eqs1: [ eqs[1], eqs[1]-eqs[2] ];
solve(eqs1, [u,v]) =>
[[u = -(sqrt(34) + 6) / 2, v = (sqrt(2)*sqrt(17) + 6) /
2],
[u = (sqrt(34) - 6) / 2, v = -(sqrt(2)*sqrt(17) - 6) / 2]]
That solution is correct, as you can verify with subst
followed by radcan.
For that matter, eliminate also works.
Maxima 5.9.0/W2k
tested with both gcd:subres and gcd:spmod
Found starting with a problem report submitted by Kirk
Lancaster (27 Nov 2003).
Logged In: YES
user_id=895922
Maxima can't even solve a triangular form of these equations:
(%o5) [2*v^2-12*v+1,v^2-2*v+u^2+10*u+1]
(%i6) algsys(%,[v,u]);
(%o6) []
Eliminating v^2 in the second equation allows Maxima to finish:
(%i7) [%o5[1],ratsubst((12*v-1)/2,v^2,%o5[2])];
(%o7) [2*v^2-12*v+1,(8*v+2*u^2+20*u+1)/2]
(%i8) algsys(%,[v,u]);
(%o8) [[v=-(sqrt(2)*sqrt(17)-6)/2,u=-(sqrt(34)+14)/2],...]
algsys can now solve the triangular form ot the equations after fixing [bugs:#3208]
Related
Bugs:
#3208Last edit: David Billinghurst 2016-10-06
I have traced this with git HEAD (after recent commits [2986fc] and [640ca7] ) and reproduced the process manually.
algsys rejects the first solution as 4sqrt(34)+(sqrt(2)sqrt(17)-6)^2/2+2(sqrt(2)sqrt(17)-6)-23 isn't simplified to zero by new function simplify-after-solve, which use sqrtdenest and ratsimp() with algebraic=true.
Even sqrt(34)-sqrt(2)*sqrt(17) defies ratsimp().
rootscontract() will simplify this this. What else does it do?
Related
Commit: [2986fc]
Commit: [640ca7]
Fixed in commit [cb3dc1]. Following tests added to testsuite.
Related
Commit: [cb3dc1]