About HP Prime factorization

[dah145]

(11-03-2020 03:46 AM)dah145 Wrote:  

(11-02-2020 07:32 PM)Albert Chan Wrote:  Hi, dah145

You can isolate the terms to be factorize, like this.

XCas> factor2(mess,s) := poly2symb(factor(symb2poly(mess,s)),s)

XCas> factor2(a^2 - 2*a*b + b^2 + s^2, a)       → b^2+s^2+a*(a-2*b)
XCas> factor2(a^2 - 2*a*b + b^2 + s^2, s)       → s^2+(a-b)^2

Yes thanks, this definitely is what I was looking for. Now I wonder if it is possible to obtain the expressions in form of a product, say: (a^2 - 2*a*b + b^2 + s^2)*(a^2 - 2*a*b + b^2 + s^2) = (s^2+(a-b)^2)*(s^2+(a-b)^2), as using your custom function outputs a not so friendly expression: s^2*(2*(a^2 + b^2) + s^2)+(a+b)^2*(a-b)^2.

Just wanted to update, I wrote a little program that factorizes polynomials to a more friendly expression than the built in factor function, I attached an example. A is the expression and B is the variable to factorize.

PHP Code:

#cas
facto(A,B):=

BEGIN
LOCAL fac, coe, pola, polb;
fac:=factors(A);
coe:={0};
polb:=[0];

FOR N FROM 1 TO SIZE(fac)/2 DO
coe[N]:=coeff(fac[2*N-1],B);
END;

pola:=factor(coe);

FOR N FROM 1 TO SIZE(fac)/2 DO
polb[N]:=poly2symb(pola[N],B);
END;

RETURN regroup(product(polb[n]^(fac[2*n]),n,1,SIZE(polb)));

END;
#end