// this function initializes the random number generator:
void CRandomMother::RandomInit (int seed) {
int i;
uint32_t s = seed;
// make random numbers and put them into the buffer
for (i = 0; i < 5; i++) {
s = s * 29943829 - 1;
x[i] = s;
}
// randomize some more
for (i=0; i<19; i++) BRandom();
}
double TRanrotWGenerator::Random() {
// returns a random number between 0 and 1.
uint32 z = BRandom(); // generate 64 random bits
switch (Architecture) {
case EXTENDEDPRECISIONLITTLEENDIAN:
// 80 bits floats = 63 bits resolution
randbits[1] = z | 0x80000000; break;
case LITTLEENDIAN:
// 64 bits floats = 52 bits resolution
randbits[1] = (z & 0x000FFFFF) | 0x3FF00000; break;
case BIGENDIAN:
// 64 bits floats = 52 bits resolution
randbits[0] = (randbits[0] & 0x000FFFFF) | 0x3FF00000; break;
case NONIEEE: default:
// not a recognized floating point format. 32 bits resolution
return (double)z * (1./((double)(uint32)(-1L)+1.));}
return (double)(randp1 - 1.0);}
// returns integer random number in desired interval:
int CRandomMother::IRandom(int min, int max) {
// Output random integer in the interval min <= x <= max
// Relative error on frequencies < 2^-32
if (max <= min) {
if (max == min) return min; else return 0x80000000;
}
// Assume 64 bit integers supported. Use multiply and shift method
uint32_t interval; // Length of interval
uint64_t longran; // Random bits * interval
uint32_t iran; // Longran / 2^32
interval = (uint32_t)(max - min + 1);
longran = (uint64_t)BRandom() * interval;
iran = (uint32_t)(longran >> 32);
// Convert back to signed and return result
return (int32_t)iran + min;
}
void TRanrotWGenerator::RandomInit (uint32 seed) {
// this function initializes the random number generator.
int i, j;
// make random numbers and put them into the buffer
for (i=0; i<KK; i++) {
for (j=0; j<2; j++) {
seed = seed * 2891336453UL + 1;
randbuffer[i][j] = seed;}}
// set exponent of randp1
randbits[2] = 0; randp1 = 1.0;
// initialize pointers to circular buffer
p1 = 0; p2 = JJ;
// store state for self-test
memcpy (randbufcopy, randbuffer, 2*KK*sizeof(uint32));
memcpy (randbufcopy[KK], randbuffer, 2*KK*sizeof(uint32));
// randomize some more
for (i=0; i<31; i++) BRandom();
}
// returns a random number between 0 and 1:
double CRandomMother::Random() {
return (double)BRandom() * (1./(65536.*65536.));
}
