C:/Musimathics_local/Musimat/MusimatChapter9/C091204a.cpp File Reference

#include "MusimatChapter9.h"

Go to the source code of this file.

Functions
	MusimatChapter9Section (C091204a)
IntegerList	randomRow (Integer N)
Static Void	para1 ()

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Function Documentation

MusimatChapter9Section

(

C091204a

)

Definition at line 2 of file C091204a.cpp.

References para1().

                                 {
Print("*** Sampling without Replacement ***");
/*****************************************************************************

Sampling without Replacement

We can generate a randomly selected 12-tone row, for example, 
by putting 12 balls in an urn, each marked with one of the chromatic pitch classes, and draw them out 
one at a time without replacement, thereby guaranteeing that no pitch class is chosen more than once.

Random(0, 11) returns a random integer between 0 and 11 with equal probability. But it could 
return the same value multiple times, so we must keep track of which pitch classes have been cho-
sen to ensure that it eventually picks one of each. This function takes one argument, N, determining 
the length of the row.
*****************************************************************************/
        para1(); // Step into this function to continue.
}

Static Void para1

(

)

Definition at line 41 of file C091204a.cpp.

References randomRow().

                    {
/*****************************************************************************
Note that the second loop keeps repeating over and over until Random() has finally selected 
all N pitch classes. It then returns the newly created 12-tone row in M. 
*****************************************************************************/
        Print("*** Random Row ***"); 
        Print("A random row:", randomRow(12));

/*****************************************************************************
Here is an example row created by randomRow(): 

{0, 6, 2, 9, 7, 5, 4, 10, 8, 3, 1, 11}; 

Every pitch class is represented exactly once.
*****************************************************************************/
}}

IntegerList randomRow

(

Integer

N

)

Definition at line 20 of file C091204a.cpp.

References Random(), and x.

                                 {
        IntegerList L;                                          // keep track of pitches chosen so far
        IntegerList M;                                          // used to build up random 12-tone row
        Integer i;
        
        // set all list elements to zero, which means "unused"
        For (i = 0; i < N; i = i + 1) {L[i] = 0;}

        // build up M, marking off elements in L when they are chosen
        i = 0;
        While (i < N) {
                Integer x = Random(0, N - 1);           // returns integer random value
                If (L[x] == 0) {                                        // hasn’t been chosen yet?
                         L[x] = 1;                                              // mark it "used"
                         M[i] = x;                                              // save result
                         i = i + 1;                                     // increment control variable
                }
        }
        Return(M);
}

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