Random double

[qznc]

Tue, 23 Apr 2013 16:43:14 +0200: qznc wrote

> I want to generate a random "double" value, excluding wierdos like NaN
> and Infinity. However, std.random.uniform seems to be useless. I tried
> things like
> 
>    std.random.uniform( double.min, double.max);
>    std.random.uniform(-double.max, double.max);
>    std.random.uniform(0.0, double.max);
> 
> However, I just get Inf values. :(
> 
> I assume this is due to floating point computation within uniform, which
> easily becomes Inf, if you come near the double.max boundary. Should
> that be considered a bug? Nevertheless, any ideas how to work around
> that issue?

Using a union seems to be a good workaround:

  union foo { ulong input; double output; }
  foo val = void;
  do {
  	val.input = uniform(ulong.min, ulong.max);
  } while (val.output == double.infinity
        || val.output == -double.infinity
        || val.output != val.output);
  return val.output;

Maybe the implementation of uniform should use a similar trick?