From
http://www.agner.org/random/
Note: this is a typical pseudo-random number generator (note that most random number generators are pseudo; the only true random number generators rely on some allegedly truly random input, such as observations of quantum mechanical behavior).
Mother-of-All
pseudo random number generator
This is a so-called multiply-with-carry or recursion-with-carry generator, invented by George Marsaglia
Algorithm:
S = 2111111111 · Xn-4 + 1492 · Xn-3 + 1776 · Xn-2 + 5115 · Xn-1 + C
Xn = S modulo 232
C = floor(S / 232)
The last four X'es and C are stored in a buffer as 32-bit unsigned integers. The intermediate S is a 64-bit unsigned integer.
The X'es and C are initialized to random values based on a seed. They cannot all be zero.
This algorithm is most effectively implemented in assembly language where you have an instruction for multiplying two 32-bit integers and get a 64-bit product. In high level languages you do not have such an instruction, so you have to use floating point numbers with a mantissa of at least 63 bits. Not all compilers support this precision, for example Microsoft Visual C++ does not.
Specifications:
* 32-bit integer output
* cycle length is 3x10^47
* very good randomness
http://www.agner.org/random/
Note: this is a typical pseudo-random number generator (note that most random number generators are pseudo; the only true random number generators rely on some allegedly truly random input, such as observations of quantum mechanical behavior).
Mother-of-All
pseudo random number generator
This is a so-called multiply-with-carry or recursion-with-carry generator, invented by George Marsaglia
Algorithm:
S = 2111111111 · Xn-4 + 1492 · Xn-3 + 1776 · Xn-2 + 5115 · Xn-1 + C
Xn = S modulo 232
C = floor(S / 232)
The last four X'es and C are stored in a buffer as 32-bit unsigned integers. The intermediate S is a 64-bit unsigned integer.
The X'es and C are initialized to random values based on a seed. They cannot all be zero.
This algorithm is most effectively implemented in assembly language where you have an instruction for multiplying two 32-bit integers and get a 64-bit product. In high level languages you do not have such an instruction, so you have to use floating point numbers with a mantissa of at least 63 bits. Not all compilers support this precision, for example Microsoft Visual C++ does not.
Specifications:
* 32-bit integer output
* cycle length is 3x10^47
* very good randomness