Pseudo random numbers between -1 and 1 (Pseudocode)

Direct link:
Tips und Tricks #9

Bezug:
General programming techniques

Details:
To generate (pseudo) random numbers in range of -1 and 1 you can do the following:

In case your rand() function returns numbers between MININT / MAXINT / MINDOUBLE / MAXDOUBLE or whatever:
cos( rand() ); // The cosine will return a number in range of -1 and 1.


In case your rand() function returns values between 0.0 and 1.0:
r = rand();
if( rand() % 2 == 0 ) // Switch sign randomly
r = -r;


Note:
It's not a real big problem that the cosine is deterministic due to the fact that random isn't really perfect, too. Hence this is pseudo random number generation.