For javascript mod I use these: function modn(a,b){ return a-Math.round(a/b)*b } // this returns in the cycle -0.5 to 0.5 function modp(a,b){ return a-M

For javascript mod I use these: function modn(a,b){ return a-Math.round(a/b)*b } // this returns in the cycle -0.5 to 0.5 function modp(a,b){ return a-Math.floor(a/b)*b } // this returns 0 to 1 (times the cycle `b`) They can actually run faster than the % operator for some reason, although not if put on Numbers prototype which is still quite slow on latest engines. I ran a quick check on possible rounding differences with % - compared results of a few million very large random number inputs: For positive Integers modp(a,b) returns identically to a%b For positive reals 8% of returns differ by about 1 ulp.