![]() My knowledge of floating-point math and RNGs isn't up to explaining why, or what you might do about that. īut I should give a word of caution: they've put a lot of effort into making sure that output of rand gives an appropriate distribution of any given double within (0,1), and I don't think you're going to get the same nice properties on if you apply the scaling I suggested. So x = (rand-eps/2)/(1-eps) should give you values on the closed interval. ![]() (Use format hex to display enough precision to check that at the bit level). You can scale this interval to by subtracting eps/2 and dividing by 1-eps. Therefore, it's equivalent to drawing from the closed interval, or. (See doc RandStream.list, and then "Choosing a Random Number Generator" for info on other generators). For Mersenne twister, the default algorithm, the possible values are all multiples of 2^(-53), within the open interval (0,1). The precise set varies depending on the RNG algorithm used. With a research staff consisting of some of the world's preeminent minds, RAND has been expanding the boundaries. RAND focuses on the issues that matter most such as health, education, national security, international affairs, law and business, the environment, and more. However, since it produces doubles, there are only a finite number of values that it will actually produce. The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. This was more clearly documented in previous versions, but it's still stated in the help text for rand (type help rand rather than doc rand). Rand produces numbers from the open interval (0,1), which does not include 0 or 1, so you should never get those values. There are so many possible outputs, all of them equally likely, that the probability of any given output is virtually zero. You "never" see rand ever outputting exactly 1/4, either. Even if rand were of type (1) above, and thus could produce 0 and 1, it would produce them with probability so small that you would "never" see those values.ĭoes that sound strange? Well, that happens with any number. Therefore, you shouldn't worry about that: in either case the probability is zero for practical purposes. So the probability is either strictly zero or so small it can be neglected. If the random generator produces values from the open interval (0, 1), the probability of getting a value 0, or 1, is strictly zero. ![]() If you have a random generator that produces values of type double on the closed interval, the probability of getting the value 0, or 1, is not zero, but it's so small it can be neglected. You can always ask an expert in the Excel Tech Community or get support in the Answers community.Mathematically, if you sample from a (continuous) uniform distribution on the closed interval, values 0 and 1 (or any value, in fact) have probability strictly zero. ![]() Note: When a worksheet is recalculated by entering a formula or data in a different cell, or by manually recalculating (press F9), a new random number is generated for any formula that uses the RAND function. You can adjust the column widths to see all the data, if needed.Ī random number greater than or equal to 0 and less than 1Ī random number greater than or equal to 0 and less than 100Ī random whole number greater than or equal to 0 and less than 100 For formulas to show results, select them, press F2, and then press Enter. The formula will calculate and leave you with just a value.Ĭopy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. If you want to use RAND to generate a random number but don't want the numbers to change every time the cell is calculated, you can enter =RAND() in the formula bar, and then press F9 to change the formula to a random number. To generate a random real number between a and b, use: The RAND function syntax has no arguments. ![]() Note: As of Excel 2010, Excel uses the Mersenne Twister algorithm (MT19937) to generate random numbers. ![]()
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