1) In MPLAB XC8 Compiler Guide;
srand() and rand() functions are demonstrated in page 399
http://ww1.microchip.com/downloads/en/devicedoc/50002053g.pdf
==========================
#include
#include
#include
void main (void)
{
time_t toc;
int i;
time(&toc);
srand((int)toc);
for(i = 0 ; i != 10 ; i++)
printf("%d\t", rand());
putchar(’\n’);
}
==========================
2) In random.org a sequence generator is demostrated with true random values
https://www.random.org/sequences/
3) IN PIC MCU without random number generator hard ware only pseudo random numbers are possible
4) My question is how can I generate pseudorandom numbers without any repetation like in random.org ? Is there a stable way ?
e.g. pseudorandom number sequence without repetation between [1-9] ?
An answer and a question.
A: random.org uses sampling of a natural phenomenon as a means of arriving at random numbers. There are significant difficulties with assurance the absence of bias and presence of acceptable randomness, with regard to the inability to predict continuation of a sequence. There are pseudo-random sequences that can be close to this, and they are often "seeded" and reseeded with natural sources.
Q: What do you mean, without repetition? You mean the sequence itself starts over and repeats completely in some (hopefully-lengthy) sequence? What you usually want is something with an extremely long period, and find a way to start at a random place in it.
PS: In some situations, such as cryptography, one wants a deterministic pseudo-RNG because we want a recipient to be able to reproduce the sequence used by the sender of a cryptogram. The seed is part of a shared secret that is exchanged between the two parties. Ideally, it is produced randomly :).
I am working on neurological tests for athletes.
I need non repating random numbers between 1 and 9
I change seed value everytime test begins and write seed value to EEPROM.
EEPROM read write works fine.
I found the problem. I had a minor problem in the algoritm which compares numbers.
Many thanks
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