TASKSIM(3CC4)TASKSIM(3CC4)NAMEtasksim - histogram and random numbers for the task library
SYNOPSIS
#include <task.h>
struct histogram {
// exported data members
int l, r; // Left and right boundaries of the histogram
int binsize; // Size of each bin
int nbin; // Number of bins
int* h; // Pointer to storage
long sum; // Sum of all entries
long sqsum; // Sum of squares of all entries
// exported constructor
histogram(int bins=16, int left=0, int right=16);
// exported functions
void add(int val);
void print();
};
class randint {
public:
// exported constructor
randint(long seed=0);
// exported functions
int draw();
float fdraw();
double ddraw();
void seed(long);
};
class urand: public randint {
public:
// exported data members
int low, high;
// exported constructor
urand(int lo, int hi);
// exported function
int draw();
};
class erand : public randint {
public:
// exported data members
int mean;
// exported constructor
erand(int m);
// exported function
int draw();
};
DESCRIPTION
The task library provides classes for gathering data and generating
random numbers. These are particularly useful in simulations.
Histograms
histogram hist(bins, left, right);
Constructs an empty histogram object hist. It contains bins
number of bins, from hist.h[0] through hist.h[bins-1]. Argu‐
ments left and right, which are ints, are assigned to data mem‐
bers l and r, respectively, and are the left and right endpoints
of the histogram. The default values are 16 bins covering the
range 0 through 16.
hist.add(val)
Adds one to the bin corresponding to value val of the histogram,
where val is an int. Updates data members sum and sqsum. If
val is outside the range l to r, the range is automatically
extended by successive doubling to include it. The number of
bins remains the same, however, so each bin will be widened pro‐
portionally and the counts adjusted to reflect the extended
range.
hist.print()
Prints on stdout (not cout) the count of entries in each non-
zero bin of histogram hist.
Random Numbers
The task library provides three classes which generate pseudo-random
numbers, with uniform or exponential distribution. Each class object
provides an independent series of pseudo-random values.
Class randint provides uniformly-distributed random numbers in the
range 0 through INT_MAX.
randint ri(s);
Creates a randint object ri. The long argument is optional, and
sets the starting seed of the generator for this object.
int i = ri.draw();
Returns the next uniformly-distributed pseudo-random value in
the sequence as an int in the closed interval [0 .. INT_MAX].
float f = ri.fdraw();
Returns the next uniformly-distributed pseudo-random value in
the sequence as a float in the half-open interval [0.0 .. 1.0).
double d = ri.ddraw();
Returns the next uniformly-distributed pseudo-random value in
the sequence as a double in the half-open interval [0.0 .. 1.0).
ri.seed(s)
Re-initializes the generator using the supplied long value as
the seed.
Class urand is derived from randint, and provides uniformly-distributed
random numbers in a specified range.
urand ur(lo, hi);
Creates a urand object ur. The long arguments represent the low
and high values of the range.
int i = ur.draw();
Returns the next uniformly-distributed pseudo-random value in
the sequence as an int in the closed interval [lo .. hi].
Class erand is derived from randint, and provides exponentially-dis‐
tributed random numbers about a specified mean.
erand er(m);
Creates an erand object er. The int argument is the mean of the
distribution.
int i = er.draw();
Returns the next exponentially-distributed pseudo-random value
in the sequence as an int about the mean. This function uses
the log function from the C math library, so programs must be
linked using -lm.
DIAGNOSTICS
See task(3CC4).
SEE ALSOtask.intro(3CC4), interrupt(3CC4), queue(3CC4), and task(3CC4).
07 August 2000 TASKSIM(3CC4)
