Working with random numbers in FileMaker

When you want random numbers, you can use FileMakers function random. It is a very simple function. It does not require any parameter and returns a number between 0 and 1. Of course, often the random numbers you are looking for do not belong to this narrow interval. You have to transform the value to match your target range.

random.interval

I wrote a little custom function to accomplish this transformation. The function expects two parameters, the lower (min) and the upper value (max) of the target interval.

random.interval( _min; _max )

Random * ( _max - _min ) + _min

This is very simple. But often you are looking for discrete values, like throwing some dice.

random.discrete

The next custom function will take care of that. As you can see, I do not only floor the random value. Because of the discrete nature of the return value, I adjust the interval limit accordingly.
This call will return the random values of a single die: random.discrete( 1; 6 ).

random.discrete( _min; _max )

Floor( Random * ( _max - _min + 1 ) ) + _min

Random is not Random

Be careful, though, with random numbers. In any real life situations random numbers are not evenly distributed. More often they follow a distribution called Normal distribution or Gauss distribution. The graph of the probability density function is bell-shaped. It has a peak at the mean, and is known as the Gaussian function or Bell curve.

Unfortunately, the FileMaker function Random returns only uniformly distributed random numbers. But mathematics offers a solution. There are actual multiple ways to convert uniformly distributed numbers to normal distributed numbers.
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