HP Forum Archive 21

[ Return to Index | Top of Index ]

HP Prime: CAS taylor Message #1 Posted by Alberto Candel on 10 Dec 2013, 7:16 p.m. Hi, In CAS, for example, if I input taylor(LN(1+x),x,3) the output is x -(1/2)*x^2+(1/3)*x^3+x^4*order_size(x) as expected from the documentation. But taylor((x+x^2+2*x^3)/(1+2*x-x^2+6*x^3), x,3) outputs x-x^2+5*x^3-17*x^4+x^5*order_size(x) instead of x-x^2+5*x^3+x^4*order_size(x) Why the extra term?

Re: HP Prime: CAS taylor Message #2 Posted by parisse on 11 Dec 2013, 4:42 a.m., in response to message #1 by Alberto Candel The third parameter is the order used for series expansion, not necessarily the final order.

Re: HP Prime: CAS taylor Message #3 Posted by Alberto Candel on 11 Dec 2013, 8:20 a.m., in response to message #2 by parisse Thank you. So if I want to obtain the Taylor polynomial of degree n of a function f(x), what is the correct command to use? (I want the result to be a polynomial of degree less than or equal to n, and I do not want the extra "order_size" term)

Re: HP Prime: CAS taylor Message #4 Posted by parisse on 12 Dec 2013, 4:02 a.m., in response to message #3 by Alberto Candel rem(convert(series(expression,x=limit_point,order),polynom),x^(order+1)) should do that: convert(.,polynom) will remove the order_size remainder term, and rem will remove all monomials of degree>=order+1. You have no warranty to get the full Taylor expansion however, since the remainder term has been erased...

Re: HP Prime: CAS taylor Message #5 Posted by Alberto Candel on 13 Dec 2013, 9:41 p.m., in response to message #4 by parisse Thanks. But it looks that such command is not available in the HP prime. The example in page 157 of the "Symbolic algebra and Mathematics with Xcas" convert(series(sin(x),x=0,6),polynom) outputs "Error: Unmatch control word"

Re: HP Prime: CAS taylor Message #6 Posted by Alberto Candel on 13 Dec 2013, 9:45 p.m., in response to message #5 by Alberto Candel But it looks like "truncate" is in Prime, and does more or less the same.

[ Return to Index | Top of Index ]

Go back to the main exhibit hall