If the input clusters near zero, there will be too few results at n - 1 in the latter solution. The Math.sign () is a built-in method in JavaScript and is used to know the sign of a number, indicating whether the number specified is negative or positive.
Math.random java negative or positive full#
If the input is random in the full range of an int, the distribution of both two solutions will be the same. The results for the above with n = 3: x | result Construct a Random object at application startup: Random random new Random () Then use Random.nextInt (int): int randomNumber random.nextInt (max + 1 - min) + min Note that the both lower and upper limits are inclusive.
Math.random java negative or positive mod#
If you only need a uniform distribution between 0 and n-1 and not the exact mod operator, and your x's do not cluster near 0, the following will be even faster, as there is more instruction level parallelism and the slow % computation will occur in parallel with the other parts as they do not depend on its result. Return ((remainder > 31) & n) + remainder
if remainder is negative, adds n, otherwise adds 0 The fastest way to do this without floorMod is like some other answers here, but with no conditional branches and only one slow % op.Īssuming n is positive, and x may be anything: int remainder = (x % n) // may be negative if x is negative Its possible that the JVM has an intrinsic optimized stub for it, however, which would speed it up significantly. The fastest being combination of Math.round () and Math.random: // randomsign -1 + 2 x (0 or 1) randomsign -1 + Math.round (Math. Each comparison is either positive or negative (very occasionally it will be 0 as well), so it will not be just ascending or descending most of the time, it will be random.Java 8 has Math.floorMod, but it is very slow (its implementation has multiple divisions, multiplications, and a conditional). There are really lots of ways to do it as previous answers show. So you’re just returning a random positive or negative number when you compare every two elements in turn, and JS will sort randomly. If inconsistent results are returned then the sort order is undefined.
If compareFunction(a, b) is greater than 0, sort b to a lower index than a.ĬompareFunction(a, b) must always return the same value when given a specific pair of elements a and b as its two arguments.Mozilla versions dating back to at least 2003) respect this. Can I generate negative numbers using Math.random If yes, how can I do this Codecademy Forums Math.random to generate negative numbers. Note: the ECMAscript standard does not guarantee this behaviour, and thus not all browsers (e.g. If compareFunction(a, b) returns 0, leave a and b unchanged with respect to each other, but sorted with respect to all different elements. Determining the sign of a number is super easy now with ES6s Math.sign It will indicate whether the number is positive, negative or zero.If compareFunction(a, b) is less than 0, sort a to an index lower than b, i.e.If a and b are two elements being compared, then: If compareFunction is supplied, the array elements are sorted according to the return value of the compare function.
0 kommentar(er)
