get the complex linear factors of a real poly
Publié : ven. avr. 27, 2018 12:14 pm
Hi,
is there no way to use the command factors to get (a list of) the complex linear factors of a real univariate polynomial? I want something like "factors" but for complex factors. There is cFactor but the return does not seem to be a list but an expression (can we make it return me a list?). There is cZeros but that does not specifically give me multiplicity and it seems to be somehow inconsistent, here is a python code:
Edit: The undocumented field extension factorisation works. I can use factors(x**2+1,i). I keep on forgetting this because I check the (english, cascmd_en.pdf p.153) documentation. I will "edit" the pdf to make sure I see it if I search the documentation. Though it will be nice if this could also be added to the documentation.
Jose
is there no way to use the command factors to get (a list of) the complex linear factors of a real univariate polynomial? I want something like "factors" but for complex factors. There is cFactor but the return does not seem to be a list but an expression (can we make it return me a list?). There is cZeros but that does not specifically give me multiplicity and it seems to be somehow inconsistent, here is a python code:
We also get the same behaviour above in XCas.f=giac("x**2+1")
g=f*f
g.cZeros() #returns [i,-i,i,-i], does it want to show me the multiplicities?
g=giac("(x**2+1)**2")
g.cZeros() #return [i,-i], bug? this does not give me multiplicity
Edit: The undocumented field extension factorisation works. I can use factors(x**2+1,i). I keep on forgetting this because I check the (english, cascmd_en.pdf p.153) documentation. I will "edit" the pdf to make sure I see it if I search the documentation. Though it will be nice if this could also be added to the documentation.
Jose