dear Stefan first of all sin(pi/2) = 1.0 to understand the problem arises in your computation u should read about floating point arithmetic and about how numbers are stored in computers. check this very good article. http://docs.sun.com/source/806-3568/ncg_goldberg.html
i hope this may clarify your doubts On Wed, Mar 17, 2010 at 3:26 AM, Laurent <moky.m...@gmail.com> wrote: > stefan.o...@gmail.com ha scritto: > > Hello, >> >> I have a term t that I simplify with t.simplify_trig(). Parts of the >> result look something like this: >> >> 65*sin(0.500000000000000*pi)*sin(x2)*cos(x3)*sin(x5)+... >> >> My limited math understanding tells me that sin(0.5*pi) is zero, >> >> > > sin(pi/2)=0, that's rignt > But 0.500000000000 probably means 0.5+10^(-15) or something like that. > You should say from what computation comes that 0.5000. > > By the way, > sage : numerical_approx(1/2)-1/2 > 0.000000000000000 > > I guess Sage does not consider the result of numerical_approx() as an exact > value : > print type(numerical_approx(1/2)) > print type(1/2) > > <type 'sage.rings.real_mpfr.RealNumber'> > <type 'sage.rings.rational.Rational' > > My two cents > > Laurent > > > > > -- > To post to this group, send email to sage-support@googlegroups.com > To unsubscribe from this group, send email to > sage-support+unsubscr...@googlegroups.com<sage-support%2bunsubscr...@googlegroups.com> > For more options, visit this group at > http://groups.google.com/group/sage-support > URL: http://www.sagemath.org > -- Ajay Rawat Kalpakkam, IGCAR ------------------------------------------------------------------------- Save Himalayas.... ------------------------------------------------------------------------- -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
