About HP Prime factorization

11022020, 06:28 AM
Post: #1




About HP Prime factorization
Sorry if this had been specifically asked before, I searched but couldn't find anything.
Suppose I want to factorize the expression: a*s^(2) + b*s + c for the variable s. In other CAS systems this could be done simply by specifying it inside the factor(expression,var) function, in calculators such as the TI 89, see image attached. I haven't found a way to achieve this on the HP Prime as its factor function doesn't work the same way. 

11022020, 07:58 AM
(This post was last modified: 11022020 07:59 AM by parisse.)
Post: #2




RE: About HP Prime factorization
factor factors over the field of coefficients of the arguments. If you want to extend this field, you must give a 2nd argument specifying the extension.
For example Code: P:=a*s^2+b*s+c; 

11022020, 05:40 PM
Post: #3




RE: About HP Prime factorization
[quote='parisse' pid='138432' dateline='1604303926']
factor factors over the field of coefficients of the arguments. If you want to extend this field, you must give a 2nd argument specifying the extension. For example Code: P:=a*s^2+b*s+c; Thank you very much, never would have guessed that, but it makes sense. Now, just another question, let's say I want to factor the expression: a^2 2*a*b+b^2+s^2, it's easy to see that it is equivalent to: s^2 + (ab)^2. I know I can get to the second expression in the HP Prime by applying the factor function like this: factor(a^2 2*a*b+b^2)+s^2, but the point if it is possible for it to be done automatically with a function. This is particularly useful, for example, to getting the simplified expressions of typical laplace transforms with symbolic coefficients, such as the ones attached. 

11022020, 07:32 PM
Post: #4




RE: About HP Prime factorization
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*(a2*b) XCas> factor2(a^2  2*a*b + b^2 + s^2, s) → s^2+(ab)^2 

11032020, 03:46 AM
Post: #5




RE: About HP Prime factorization
(11022020 07:32 PM)Albert Chan Wrote: Hi, dah145 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+(ab)^2)*(s^2+(ab)^2), as using your custom function outputs a not so friendly expression: s^2*(2*(a^2 + b^2) + s^2)+(a+b)^2*(ab)^2. 

11192020, 04:12 PM
(This post was last modified: 11192020 10:00 PM by dah145.)
Post: #6




RE: About HP Prime factorization
(11032020 03:46 AM)dah145 Wrote:(11022020 07:32 PM)Albert Chan Wrote: Hi, dah145 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 

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