the accuracy of solve seems to depend on the order of variables and/or equations in some cases, e.g.
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solve(grad(x^2-y^2-lambda*(x^3+y^3-3*x*y),[x,y,lambda]),[x,y,lambda])
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[[0,0,sqrt(2*(sqrt(13)-1)/9)],[-expr("rootof([[1,-65,203,-2035],[1,0,10,-936,-3251]])",0)/4032,-expr("rootof([[1,-2,-49,-838],[1,0,10,-936,-3251]])",0)/504,sqrt(2*(sqrt(13)-1)/9)],[0,0,-(sqrt(2*(sqrt(13)-1)/9))],[-expr("rootof([[1,-2,-49,-838],[1,0,10,-936,-3251]])",0)/504,-expr("rootof([[1,-65,203,-2035],[1,0,10,-936,-3251]])",0)/4032,-(sqrt(2*(sqrt(13)-1)/9))],[0,0,lambda]]
Code : Tout sélectionner
solve(grad(x^2-y^2-lambda*(x^3+y^3-3*x*y),[lambda,x,y]),[lambda,x,y])
Code : Tout sélectionner
[[lambda,0,0],[0.760927982497,1.45681504207,0.845960595657]]