On Mon, Dec 13, 2010 at 12:16 PM, Chris Seberino <cseber...@gmail.com> wrote: > > OK thanks for your help. I think I got it. The effect of RealField > is like creating a new number type. I need to make sure all my real > are of the right type. It appears integers are fine as is.
Yes, exactly. Exact types (e.g. integers, rationals, symbolic expressions) will get converted to the correct degree of precision. > Here is working code... > > def test(big): > my_pi = RealField(big)(pi) > ten = RealField(big)(10.0) > constant = 100 * sqrt(my_pi/log(ten)) > ten_thou = RealField(big)(10000.0) > f(k) = ten^(-k^2/ten_thou) > the_sum = RealField(big)(sum(f(k) for k in range(-big, big + > 1))) > difference = the_sum - constant > return difference You can be a bit simpler then this. E.g. sage: R = RealField(1000) sage: constant = R(100 * sqrt(pi/log(10))) # everything exact before the cast sage: ten_thou = R(10000) sage: f(k) = 10^(-k^2/ten_thou) # result will be in R because ten_thou is sage: the_sum = sum(f(k) for k in range(-1000, 1001)); the_sum 116.806521814573408154703961183569656583504707301922359958037591640215510813039244934779299244023546182097713963521073027455330258514764785349144281947839532827346835171962415366657291332526181608818055375581821843529213967899316532193194799347444658828139424420035706699509726059514135509142461539243 - Robert -- 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
