From Bfx_help(...)
90   ==========================Non volatile random numbers===========================
91   i is a positive integer number, b is the bottom value, t (>b) is the top value
92   <r> is an optional range
93   random_number = BfX_Ran(i; <r>) 0 <= random_number <= 1]
94   b <= random_number <= t = BfX_Ranb(i; b; t; <r>)
95   c and s are center and width of normal distribution
96   normal distribution b <= random_number <= t= BfX_Rang(i; c; s; b; t; <r>)
97   use <r> to link cells to guide Excels calculation order

i is the seed.

<r> is a cell or a range

B   C   D
2   seed   1234567
3      
4   0,051118901   =BfX_Ran(seed)
5   0,207298019   =BfX_Ran(seed;C4)
6   0,529684412   =BfX_Ran(seed;C5)
7   0,164931189   =BfX_Ran(seed;C6)
8   0,760708209   =BfX_Ran(seed;C7)
9   0,711878956   =BfX_Ran(seed;C8)
10   0,434484066   =BfX_Ran(seed;C9)
11   0,032066679   =BfX_Ran(seed;C10)
12   0,018770791   =BfX_Ran(seed;C11)
13   0,197369616   =BfX_Ran(seed;C12)
14      
15   bfx_ran    refers to the previous cell in order to force
16      a specific order of random number (cell) processing

My random number is non volatile.
Volatile means according to MS:
Excel supports the concept of a volatile function, that is, one whose value cannot be assumed to be the same from one moment to the next even if none of its arguments (if it takes any) has changed. Excel reevaluates cells that contain volatile functions, together with all dependents, every time that it recalculates. For this reason, too much reliance on volatile functions can make recalculation times slow. Use them sparingly.

The following Excel functions are volatile:

    NOW

    TODAY

    RAND

    OFFSET

    INDIRECT

    INFO (depending on its arguments)

    CELL (depending on its arguments)

1) My random number generator generates the same output sequence for the same seed.
2) My random number generator is not recalculated if somewhere else on the spreadsheet an (unlinked) cell is recalculated.

In visual basic and as an Excel function I have published random number generators, two of them generate numbers with a constant probability ("flat").
The other one. =bfx_rang(....) generates numbers according to a gaussian distribution.
The properties of Excels random generators did not suit my purpose.

The "flat" distribution is the basis for generating numbers distributed according to another distribution.
For gaussian distributions efficient algorithms can be googled.

Nevertheless, the more random variables involved in a simulation, the less details of a certain random variable matter.

Ok,
I understand what you understand - nothing special meant here. Let me make things less abstract.

Basically what Monte Carlo does is to generate "outcomes", e.g. where a  bullet ends, for, varying conditions - the input parameters. The input parameters are varied according to a certain probability distribution. If for example a shooter is able to aim with an accuracy of 1 MoA then people like me model that as a bell-shaped (Gaussian) probability distribution that averages to 1 MoA mean inaccuracy. With this we acknowledge the fact that in some cases the shooter aims very well and in others badly. 

In a Monte Carlo simulation then, the computer draws a random number and converts that to an inital horizontal and vertical aiming angle. This is done in such a way that average inaccuracy is 1 MoA. After the horizontal and vertical launch angles are chosen, the bullets trajectory is calculated.

If, for instance, in addition the effects of a non-constant wind is being studied, one might model that primitively as a wind distribution that is half of the time zero and the other half 1 m/s. In a Monte Carlo calculation then one first draws a random number that determines the launch angle, and an another random number is used to determine if there is wind or not in the trajectory calculation (with the afforementioned spreadsheet I deal on a more sophisticated way with non constant wind along a trajectory). Hence we end up with a set of bullet end coordinates that  were affected by both wind and the shooters abilities.

In practise, the more inputs one generates according to a probability distribution, the less the details of a probability distribution matters. The distribution might as well be flat, meaning that the probability for a certain input value is constant in a certain range and zero elsewhere.

Maybe "Monte Carlo" is a  definition issue. In this case, i imagined that input parameters are generated in such a way that they are consistent with a certain probability distribution. Then a trajectory calculated and evaluated. The process is repeated hundreds of times. This is what one might describe as Monte Carlo.

WEZ is a Monte Carlo simulation.

I find it hard to opinate about it - it does what it says.

Quite frequently I use a similar tool understand ballistic effects in a target shoot competition setting.

It is available as download on the BfX site. Look for the descriptive text:

"This workbook hosts a simulator with which you can estimate your results in a (multi distance, multi target) match, e.g. the NRA 90 shot full bore regional match course."

http://en.wikipedia.org/wiki/Buckingham_%CF%80_theorem

cool!

what I need are parametrizations of 6dof coefficients for boat tail bullets. No other projectiles.

The problem with these matters is that assumptions are made "e.g bullet flies in the direction of the wind" and presented as facts.

Even they are somewhere along the trajectory true, there is a period they are not valid. What happens then.

Nevertheless, I have time to spare I will read better the article.

Robert

Indeed, BfX does not work on a Mac.

In short I will have a look at your work!

mman has a 1000m+ range in his backyard! Shall we  ask him?

The problem, of course, is to do the measurements.

In those measurements one has to vary some quantities that affect spin drift and other factors that affect horizontal displacement. Then there is wind and measurement errors. To single out to spin-drift effects one must trust the proper computation of all other effects that deflects the bullet. I would guess that only a professional organisation is able to do the measurements.

As far as I know, the US Army is the only institution that published measurements.

Brian did the best next thing. He used a proffesional 6DOF ballistic program - PRODAS - and fitted the spin drift of bullets.

In the Netherlands there is nothing a shooter can shoot at that requires an elevation of more than a degree...

no, i cannot lay hands on a proper set of formula's for the bullet 6dof parameters.

svorog1, we need more details.

can you post the spreadsheet so that we understand what you are doing?

Sometimes I wonder what to add to BfX given that there are spreadsheets, like this one, that does so much! Clearly, being able to run on a Pocket PC brings ballistics in the field.