• lanael (19/19) Feb 17 2006 I'm getting strange readings...
• Jarrett Billingsley (13/14) Feb 17 2006 std.random.rand() returns a uint, in the range 0 to 4billion something (...
• lanael (2/6) Feb 18 2006 ah yes ! I overlooked that fact...

"lanael" <no mail.never> writes:

I'm getting strange readings...
doing that :

--------------------8<------------------
import std.random;

void main()
{
	int i;
	float f1, f2, f3;

	for(int z=0;z<20;z++)
	{
    	i=rand()%2*2-1;		// 1 or -1 random integer

		f1=rand()%2*2-1;
		f2=cast(float)(rand()%2*2-1);
		f3=i;

		printf("%f1 \t\t %f2 \t\t %f3\n",f1,f2,f3);
	}
}
-------------------->8------------------

Looks like an overflow problem, but why ??

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

"lanael" <no mail.never> wrote in message 
news:mn.8d3f7d621b84e8ba.35838 mail.never...
 Looks like an overflow problem, but why ??

std.random.rand() returns a uint, in the range 0 to 4billion something (that 
exact number that you're getting).  When you assign the result of that 
rand() expression to an int, it gets converted to a signed integer.  But 
when you put it in a float, the float is big enough to hold that number and 
so it gets stored that way.

If you replace rand() with (cast(int)rand()), the problem goes away.  Of 
course, that looks ugly, so you could make a function for it, like

int intRand()
{
    return cast(int)rand();
} 

"lanael" <no mail.never> writes:

 "lanael" <no mail.never> wrote in message 
 news:mn.8d3f7d621b84e8ba.35838 mail.never...
 Looks like an overflow problem, but why ??

 std.random.rand() returns a uint, 

ah yes ! I overlooked that fact...
it's obvious now, thanks !