/**
* Calculate the result array <code>
* [ poly1.divide(gcd(poly1, poly2)), poly2.divide(gcd(poly1, poly2)) ]</code> if the given
* expressions <code>poly1</code> and <code>poly2</code> are univariate polynomials with equal
* variable name.
*
* @param poly1 univariate polynomial
* @param poly2 univariate polynomial
* @return <code>null</code> if the expressions couldn't be converted to JAS polynomials
*/
public static IExpr[] cancelGCD(IExpr poly1, IExpr poly2) throws JASConversionException {
try {
ExprVariables eVar = new ExprVariables(poly1);
eVar.addVarList(poly2);
if (!eVar.isSize(1)) {
// gcd only possible for univariate polynomials
return null;
}
ASTRange r = new ASTRange(eVar.getVarList(), 1);
JASConvert<BigRational> jas = new JASConvert<BigRational>(r.toList(), BigRational.ZERO);
GenPolynomial<BigRational> p1 = jas.expr2JAS(poly1);
GenPolynomial<BigRational> p2 = jas.expr2JAS(poly2);
GenPolynomial<BigRational> gcd = p1.gcd(p2);
IExpr[] result = new IExpr[2];
if (gcd.isONE()) {
result[0] = jas.rationalPoly2Expr(p1);
result[1] = jas.rationalPoly2Expr(p2);
} else {
result[0] = jas.rationalPoly2Expr(p1.divide(gcd));
result[1] = jas.rationalPoly2Expr(p2.divide(gcd));
}
return result;
} catch (Exception e) {
if (Config.SHOW_STACKTRACE) {
e.printStackTrace();
}
}
return null;
}
public static boolean polynomialQ(final IExpr polnomialExpr, final IAST variables) {
try {
IExpr expr = F.evalExpandAll(polnomialExpr);
ASTRange r = new ASTRange(variables, 1);
JASConvert<IExpr> jas = new JASConvert<IExpr>(r.toList(), new ExprRingFactory());
return jas.expr2IExprJAS(expr) != null;
} catch (JASConversionException e) {
// exception will be thrown if the expression is not a JAS polynomial
}
return false;
}
@Override
public IExpr evaluate(final IAST lst) {
if (lst.size() >= 3) {
try {
if (lst.get(1).isVector() < 0) {
return null;
}
if (lst.get(2).isVector() < 0) {
return null;
}
if (lst.size() == 3) {
IAST vars = (IAST) lst.get(2);
if (vars.size() <= 1) {
return null;
}
List<ISymbol> varList = new ArrayList<ISymbol>(vars.size() - 1);
String[] pvars = new String[vars.size() - 1];
for (int i = 1; i < vars.size(); i++) {
if (!vars.get(i).isSymbol()) {
return null;
}
varList.add((ISymbol) vars.get(i));
pvars[i - 1] = ((ISymbol) vars.get(i)).toString();
}
GroebnerBasePartial<BigRational> gbp = new GroebnerBasePartial<BigRational>();
IAST polys = (IAST) lst.get(1);
List<GenPolynomial<BigRational>> polyList =
new ArrayList<GenPolynomial<BigRational>>(polys.size() - 1);
JASConvert<BigRational> jas = new JASConvert<BigRational>(varList, BigRational.ZERO);
for (int i = 1; i < polys.size(); i++) {
IExpr expr = F.evalExpandAll(polys.get(i));
GenPolynomial<BigRational> poly = jas.expr2JAS(expr);
polyList.add(poly);
}
OptimizedPolynomialList<BigRational> opl = gbp.partialGB(polyList, pvars);
// System.out.println(opl);
IAST resultList = F.List();
for (GenPolynomial<BigRational> p : opl.list) {
// System.out.println(p);
resultList.add(jas.poly2Expr(p, null));
}
return resultList;
}
} catch (JASConversionException e) {
if (Config.SHOW_STACKTRACE) {
e.printStackTrace();
}
}
}
return null;
}