D.7.4.1 nt_solve

Procedure from library ntsolve.lib (see ntsolve_lib).

Usage:

nt_solve(gls,ini[,ipar]); gls,ini= ideals, ipar=list/intvec,
gls: contains the equations, for which a solution will be computed ini: ideal of initial values (approximate solutions to start with),
ipar: control integers (default: ipar = 100,10)

ipar[1]: max. number of iterations ipar[2]: accuracy (we have the l_2-norm ||.||): accept solution sol if ||gls(sol)|| < eps0*(0.1^ipar[2]) where eps0 = ||gls(ini)|| is the initial error

Assume:

gls is a zerodimensional ideal with nvars(basering) = size(gls) (>1)

Return:

ideal, coordinates of one solution (if found), 0 else

Note:

if printlevel >0: displays comments (default =0)

Example:

LIB "ntsolve.lib";
ring rsq = (real,40),(x,y,z,w),lp;
ideal gls =  x2+y2+z2-10, y2+z3+w-8, xy+yz+xz+w5 - 1,w3+y;
ideal ini = 3.1,2.9,1.1,0.5;
intvec ipar = 200,0;
ideal sol = nt_solve(gls,ini,ipar);
sol;
→ sol[1]=0.8698104581550055082008024750939710335537
→ sol[2]=2.8215774457503246008496262517717182369409
→ sol[3]=1.1323120084664179900060940157112668717318
→ sol[4]=-1.413071026406678849397999475590194239628