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LabVIEW
How to develop a program to perform factorials?
Well, the math is very simple using shift registers, the LabVIEW code can probably fit on a postage stamp 🙂
The LabVIEW challenge that tst mentioned actually had much more difficult requirements: The input can go up to 10000 and all digits of the result needed to be exact. (In the case of n=10000, the result was a number with 35660 digits! An efficient LabVIEW program can calculate them all in under 60 milliseconds 🐵
If you do plain double precision calculations, you'll get a rounded (inexact) result for n>22 and INF for N>170. Still this might be all you need. One simple way to calculate factorials using simple DBL precision, would be similar to the code in the attached image. It is a very illustrative example to learn about shift registers. Please study it carefully, even watch it run with execution highlighting on. 🙂
The LabVIEW challenge that tst mentioned actually had much more difficult requirements: The input can go up to 10000 and all digits of the result needed to be exact. (In the case of n=10000, the result was a number with 35660 digits! An efficient LabVIEW program can calculate them all in under 60 milliseconds 🐵
If you do plain double precision calculations, you'll get a rounded (inexact) result for n>22 and INF for N>170. Still this might be all you need. One simple way to calculate factorials using simple DBL precision, would be similar to the code in the attached image. It is a very illustrative example to learn about shift registers. Please study it carefully, even watch it run with execution highlighting on. 🙂
Message Edited by altenbach on 03-14-2005 01:36 PM
Here are two more methods:
If you have LabVIEW PDS or higher, there is a factorial function built-in. Look in the "Analyze...Math...Special and numeric functions" palette.
Since the product of an empty array is defined as 1, you could also use that to calculate factorials. Since it needs to allocate an array, it is less efficient, but for the sizes involved here it does not matter.
For your task you should modify my earlier example. If you auto-index out of the loop next to the upper shift register, you will obtain a list of all factorials up to n in one swoop. This should help you create your table output. 🙂
If you have LabVIEW PDS or higher, there is a factorial function built-in. Look in the "Analyze...Math...Special and numeric functions" palette.
Since the product of an empty array is defined as 1, you could also use that to calculate factorials. Since it needs to allocate an array, it is less efficient, but for the sizes involved here it does not matter.
For your task you should modify my earlier example. If you auto-index out of the loop next to the upper shift register, you will obtain a list of all factorials up to n in one swoop. This should help you create your table output. 🙂
All three diagrams that I posted give the correct results within the ~15 decimal digit precision of DBL. Maybe you can tell us what results you are getting for n=13 and what kind of result you are expecting.
IF you are doing the calcualtion in I32, it will overflow at 13. This is a limit of the numeric representation. No surprises here. What do you expect? The recursive demo posted in this thread is done in I32 and thus is limited to inputs of 0-12. You can change it to DBL if you want. It is more a demo to show a recursive algorithm than to do any useful computation. It is way too slow anyway.
The algoritms from the factorial challenge can do inputs up to 10000, giving a result with 35660 decimal digits. 🙂
IF you are doing the calcualtion in I32, it will overflow at 13. This is a limit of the numeric representation. No surprises here. What do you expect? The recursive demo posted in this thread is done in I32 and thus is limited to inputs of 0-12. You can change it to DBL if you want. It is more a demo to show a recursive algorithm than to do any useful computation. It is way too slow anyway.
The algoritms from the factorial challenge can do inputs up to 10000, giving a result with 35660 decimal digits. 🙂
@yessyjami wrote:
Hello
Do you think you could explain in detail the last VI you copartied ?
Please
What kind of detail do you need? It's very self-explanatory.
