javascript - Math.cos inaccurancy -

javascript - Math.cos inaccurancy -

alert(math.cos(math.pi/2));

why result not exact zero? inaccurancy, or implementation error?

math.pi/2 approximation of real value of pi/2. taking exact cosine of approximated value won't yield zero. value approximation of exact value precision of underlying floating point datatype.

using arbitrary precision library, can evaluate difference between pi/2 in double precision , exact value to

0.0000000000000000612323399573676588613032966137500529104874722961...

since slope of cosine close zeros 1, expect cosine of approximation of pi/2 approximately equal difference, , indeed is.

javascript math floating-point