A bug in function sine about symbolic computation in Sagemath 7.2?

confirmed_issue

danny
173 ●3 ●9 ●20

tmonteil
27483 ●32 ●205 ●519 http://wiki.sagemath.o...

sage: n=7
sage: [RR(sin(i)) for i in [0,pi/n,..,2*pi]]
[0.000000000000000,
 0.433883739117558,
 0.781831482468030,
 0.974927912181824,
 0.974927912181824,
 0.781831482468030,
 0.433883739117558,
 0.000000000000000,
 0.433883739117558,
 0.781831482468030,
 0.974927912181824,
 0.974927912181824,
 0.781831482468030,
 0.433883739117558,
 0.000000000000000]
sage: [sin(RR(i)) for i in [0,pi/n,..,2*pi]]
[0.000000000000000,
 0.433883739117558,
 0.781831482468030,
 0.974927912181824,
 0.974927912181824,
 0.781831482468030,
 0.433883739117558,
 1.22464679914735e-16,
 -0.433883739117558,
 -0.781831482468030,
 -0.974927912181824,
 -0.974927912181824,
 -0.781831482468030,
 -0.433883739117558,
 -2.44929359829471e-16]

Comments

Why do you think this is a bug? RR has 53 bits of precision, and 1.22e-16 is sufficiently close to zero. More precisely, RR(pi) is not exactly equal to pi, so sin(RR(pi)) is not exactly equal to zero. Same with sin(RR(2*pi)).

John Palmieri ( 8 years ago )

I guess the reported issue is about wrong signs in the symbolic version, not about numerical approximation.

tmonteil ( 8 years ago )

add a comment

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

A bug in function sine about symbolic computation in Sagemath 7.2?

Comments

1 Answer

Your Answer

Question Tools

Stats

Related questions

A bug in function sine about symbolic computation in Sagemath 7.2? savecancel

Comments

1 Answer