2nd try to post ---------- Forwarded message ---------- From: Lionel Cons <[email protected]> Date: 29 January 2013 10:50 Subject: Floating point oddities with pow()? Accuracy problem? To: ast-users <[email protected]>, [email protected]
Can someone explain why the the examples below yield a difference? IMO pow() should deliver the same result as a x*x*x*... sequence. Or not? ksh -c 'float x y ; ((x=y=.1 , y=pow(y,4.) , x=x*x*x*x)) ; printf "%30.30f\n" x-y' -0.000000000000000000000006617444 ksh -c 'float x y ; ((x=y=.1 , y=pow(y,6.) , x=x*x*x*x*x*x)) ; printf "%30.30f\n" x-y' -0.000000000000000000000000103397 ksh -c 'float x y ; ((x=y=.1 , y=pow(y,8.) , x=x*x*x*x*x*x*x*x)) ; printf "%30.30f\n" x-y' -0.000000000000000000000000001615 Platform is Suse 12.1 on AMD64. Lionel -- Lionel _______________________________________________ ast-developers mailing list [email protected] http://lists.research.att.com/mailman/listinfo/ast-developers
