Random Number Generator Example
Example 9 – Random Number Generator
FILENAME: example9.cpp
#include <rw/math/funcobj.h>
#include <rw/histo.h>
#include <rw/rstream.h>
#include <rw/rand.h>
#include "myrand.h"
//**********************************************************
// Class MyRand demonstrates how to convert a function into a
// function object, which can then be used as the template
// parameter to the random number generator classes in the
// Essential Math Module.
// The function motherRNG is George Marsaglia's "Mother of all
// Random Number Generators" and is defined in mrng.cpp.
//**********************************************************
class MyRand
{
public:
// RandFtn is a typedef for a pointer to a
// function that takes an unsigned long* and returns a double:
typedef double (*RandFtn)( unsigned long * );
// Function call operator returns the random number
// by calling the function:
double operator()() { return (*randFunction_)(&randInt_); }
// Default constructor:
MyRand(unsigned long seed = 123455):randFunction_(motherRNG),
randInt_(seed) {;}
private:
unsigned long randInt_;
RandFtn randFunction_;
};
int main()
{
// Create a binomial random number generator
// using the class MyRand to generate the
// underlying uniform (0,1) deviates:
RWTRandBinomial<MyRand> randBino( 23 );
// Create a thousand random numbers and store them in a vector.
RWMathVec<double> randomNumbers( 1000, rwUninitialized );
RWMathVec<double>::iterator first = randomNumbers.begin();
RWMathVec<double>::iterator last = randomNumbers.end();
while (first != last)
*first++ = randBino();
// Put the random numbers in a histogram and print them.
Histogram h( 10U, randomNumbers );
std::cout << h << std::endl;
return 0;
}
Sample Input:
None required.
Sample Output:
HISTOGRAM:
Total number of Counts = 1000
Total number of bins = 10
Number of larger values = 0
Number of smaller values = 0
Bin number -- Bin boundaries -- Counts
0 2 3.2 54
1 3.2 4.4 89
2 4.4 5.6 123
3 5.6 6.8 163
4 6.8 8 368
5 8 9.2 97
6 9.2 10.4 53
7 10.4 11.6 35
8 11.6 12.8 10
9 12.8 14 8
