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johanna_younous
Level III

Limit to seed number

Hello everyone
I was wondering if there were an upper limit to the seed that we can define in JMP ?  Can we go up to the infinite or nearby ?   

I am concatenating  big numbers to be able to recreate the same seed each time they occur together, but as those number are increasing with time, the seed will quickly increase as well. So far everything is running fine but I may reach values close to 10^12 or 10^13  soon enough.

thanks for your answer ! 

 

regards 

 

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Limit to seed number

You can use the full 32-bit range (except 0), so you should get different random results for seeds from [1, 4294967295].  Beyond that it will wrap, so note that 4294967296 wraps to 0 and uses a random seed.  Below is @Craige_Hales script with seeds 2^32+1 and 1 to show that the random values are the same with these two seeds.

 

s1 = 4294967297;
s2 = 1;

randomreset(s1);
print("s1:",randomuniform(),randomuniform(),randomuniform());

randomreset(s2);
print("s2:",randomuniform(),randomuniform(),randomuniform());

print("bits:",hex(s1), hex(s2)); // the two numbers are almost the same, in bits

"s1:"
0.883865864481777
0.973821102175861
0.507582586025819
"s2:"
0.883865864481777
0.973821102175861
0.507582586025819
"bits:"
"41F0000000100000"
"3FF0000000000000"

 

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3 REPLIES 3
Craige_Hales
Super User

Re: Limit to seed number

It is a good question, and I don't have a precise answer. But I'm pretty sure you want to stick with integers from 1 to 2147483647 (2^31-1). After experimenting a bit:

 

s1 = 123559868338560;
s2 = 123456789123456;

randomreset(s1);
print("s1:",randomuniform(),randomuniform(),randomuniform());

randomreset(s2);
print("s2:",randomuniform(),randomuniform(),randomuniform());

print("bits:",hex(s1), hex(s2)); // the two numbers are almost the same, in bits

 

"s1:"
0.810199321946129
0.909442130941897
0.272601864300668
"s2:"
0.810199321946129
0.909442130941897
0.272601864300668
"bits:"
"42DC182183E46000"
"42DC122183E46000"

Craige

Re: Limit to seed number

You can use the full 32-bit range (except 0), so you should get different random results for seeds from [1, 4294967295].  Beyond that it will wrap, so note that 4294967296 wraps to 0 and uses a random seed.  Below is @Craige_Hales script with seeds 2^32+1 and 1 to show that the random values are the same with these two seeds.

 

s1 = 4294967297;
s2 = 1;

randomreset(s1);
print("s1:",randomuniform(),randomuniform(),randomuniform());

randomreset(s2);
print("s2:",randomuniform(),randomuniform(),randomuniform());

print("bits:",hex(s1), hex(s2)); // the two numbers are almost the same, in bits

"s1:"
0.883865864481777
0.973821102175861
0.507582586025819
"s2:"
0.883865864481777
0.973821102175861
0.507582586025819
"bits:"
"41F0000000100000"
"3FF0000000000000"

 

johanna_younous
Level III

Re: Limit to seed number

Thanx, this is very interesting.