SERIOUS Seed Bug

This is bad.

SeedRnd $24E7AC60
a=Rand(0,8)
Print a
Input b$

The random number generated is 9.

Bit of a problem when you are picking a random column for a number when generating a Sudoku puzzle when the Sudoku array is only (8,8) - Array Index out of Bounds.

So I wrote some code to see how often this happens - I stopped it from running after it found the first 9 seeds that cause Rand() to return numbers outside the specified range. That means that I only checked the first

267,250,961 positive seeds from a possible
2,147,483,647 - not counting the negative seeds.

If you run the following code, you will see that all nine of these seeds caused Rand(0,8) to return 9.

For x=1 To 9
	Read a
	SeedRnd a
	Print Rand(0,8)
Next
b$=Input$()	;for pause purposes

Data $012ADB51,$03b0c470,$04db9fc1,$076188e0,$088c6431
Data $0b124d50,$0c3d28a1,$0ec311c0,$0feded11

What's even more bizarre - given that I already know that Blitz2D doesn't generate the same random numbers from the same seeds as BlitzPlus, is that when I run the final piece of code above in Blitz2D - all of the above seeds return 8 (including the seed in the first example that caused my prog to crash).

So maybe there isn't an algorithmic difference in the random number generators afterall - just a few bugs in the BlitzPlus version.

And also in Blitz3D.

So, anything happening?

Someone wrote a better random number generator. Morduun i think? You could search the code archives.

http://www.denathorn.co.uk/Files/mersennetwist.zip

I'm sure thats it! :)

You could always work round the problem by sticking a Mod 9 On the end of it.

Print Rand(0,8) Mod 9

I accept not an ideal solution, but you won't get any out of range errors and the results will be predictable.

Funny thing when you use rnd instead of rand it works fine.