Computes the inverse of a birational map.
-- -*- M2-comint -*- {* hash: 83085708 *} |
i1 : K=QQ; |
i2 : R=K[v,u,z]; |
i3 : I=ideal(v^8-u^3*(z+u)^5); o3 : Ideal of R |
i4 : linsys=matrix {{u^6+4*u^5*z+6*u^4*z^2+4*u^3*z^3+u^2*z^4,v*u^5+3*v*u^4*z+3*v*u^3*z^2+v*u^2*z^3,v^2*u^4+3*v^2*u^3*z+3*v^2*u^2*z^2+v^2*u*z^3,v^3*u^3+2*v^3*u^2*z+v^3*u*z^2,v^4*u^2+v^4*u*z,v^5*u+v^5*z,v^6}}; 1 7 o4 : Matrix R <--- R |
Speed this up. Perhaps give as argument just phi in R/I. Does not check whether phi is birational.
The object invertBirationalMap is a method function.