i tried the algorithm with a very simple C program and this is the
output i got ,
from my visual inspection , there was no repetition for the first 98
values after which the cycle started again, this is my output
followed by a simple implementation.
Hope this helps
pdhan...@hansolo:/afs/ece.cmu.edu/usr/pdhanapa> ./a.out
Enter seed X0 5
Enter multiplier a 2
Enter c and m - relatively prime to each other0
199
10
20
40
80
160
121
43
86
172
145
91
182
165
131
63
126
53
106
13
26
52
104
9
18
36
72
144
89
178
157
115
31
62
124
49
98
196
193
187
175
151
103
7
14
28
56
112
25
50
100
1
2
4
8
16
32
64
128
57
114
29
58
116
33
66
132
65
130
61
122
45
90
180
161
123
47
94
188
177
155
111
23
46
92
184
169
139
79
158
117
35
70
140
81
162
125
51
102
5
10
20
// naive Code :P
#include<stdlib.h>
#include<stdio.h>
int main()
{
int x0,a,c,m,i,x1;
printf("Enter seed X0 ");
scanf("%d",&x0);
printf("Enter multiplier a ");
scanf("%d",&a);
printf("Enter c and m - relatively prime to each other");
scanf("%d %d",&c,&m);
for(i=0;i<=100;i++)
{
x1=( ( (a*x0) + c)% m) ;
printf(" %d \n",x1);
x0=x1;
}
}
On 10/5/09, Prabhu Hari Dhanapal <[email protected]> wrote:
> hi ,
>
> I think the Linear Congruential Generator is believed to be the most
> simple of all PRNGs.
>
> The sequence can be generated using the following,
> X(n+1) = (a* Xn +c ) mod m
>
> In the above , your first step would be
> X1 = (a*X0 +c ) mod m
>
> X0 is the seed value that you need to feed to the algorithm and it has
> no restrictions as such.
> a is a multiplier
> c is the increment and choose some value for m
>
> note that c and m should be relatively prime to each other - (such
> that they do no have any common factor except for 1 )
>
> This perfectly fits you application because, LCGs are generally not
> advisable to be used in Cryptographic algorithms - where randomness is
> critical.
>
>
>
> On 10/3/09, Brandon <[email protected]> wrote:
>>
>> Hi.
>>
>> I need a computationally simple algorithm to generate a random series
>> of discrete values, i.e., I want to get a string of integers where
>> each integer is in the range from 1 to N where N is fairly small (less
>> than 100 for sure). Has to be simple enough to run on a
>> microcontroller unit. Doesn't need to be extremely good, the sequence
>> could probably repeat after only 1000 values and sitll be okay. I
>> just don't want to someone looking at the sequence to notice any
>> obvious patterns.
>>
>> Thanks
>>
>> >>
>>
>
>
> --
> Hari
>
--
Hari
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