internal virtual Vector solve(ArrayList expr, ArrayList x, int n)
{
Algebraic equ = null;
Variable v = null;
int i, k, iv = 0, ke = 0;
for (i = 0; i < n && equ == null; i++)
{
v = ( Variable )x[i];
double norm = -1.0;
for (k = 0; k < n; k++)
{
Algebraic exp = ( Algebraic )expr[k];
if (exp is Rational)
{
exp = (( Rational )exp).nom;
}
Algebraic slope = exp.Derive(v);
if (!slope.Equals(Symbol.ZERO) && slope is Symbol)
{
double nm = slope.Norm() / exp.Norm();
if (nm > norm)
{
norm = nm;
equ = exp;
ke = k;
iv = i;
}
}
}
}
if (equ == null)
{
for (i = 0; i < n && equ == null; i++)
{
v = ( Variable )x[i];
for (k = 0; k < n; k++)
{
Algebraic exp = ( Algebraic )expr[k];
if (exp is Rational)
{
exp = (( Rational )exp).nom;
}
if (exp.Depends(v))
{
equ = exp;
ke = k;
iv = i;
break;
}
}
}
}
if (equ == null)
{
throw new SymbolicException("Expressions do not depend of Variables.");
}
Vector sol = LambdaSOLVE.solve(equ, v);
expr.RemoveAt(ke);
expr.Insert(n - 1, equ);
x.RemoveAt(iv);
x.Insert(n - 1, v);
return(sol);
}