Combinations and Permutations "Rules"

MathsIsFun · 2012-08-30 09:00:53

It may simply have run out of time ... I know it took a while on my PC.

Try a slightly smaller one and see if it works

anonimnystefy · 2012-08-30 09:50:14

Hi MIF

It works for a,a,b,c,d. But, functioning for inputs smaller than 10 input characters isn't very practical. Maybe you can use some other method for calculating their number (using e.g. a script written in a mathematical package).

bobbym · 2012-08-30 10:07:14

Hi MIF;

It may simply have run out of time ... I know it took a while on my PC.

Yes, it takes some time on mine too. It seems to be working fine for smaller ones.

anonimnystefy · 2012-08-30 10:10:39

What input did you take, bobbym?

bobbym · 2012-08-30 10:12:55

Hi;

Where?

anonimnystefy · 2012-08-30 10:18:21

bobbym wrote:

Yes, it takes some time on mine too.

What did you enter as an input (which letters) that gave the slow output?

bobbym · 2012-08-30 10:22:35

Hi;

Post #17.

anonimnystefy · 2012-08-30 10:31:36

"m,a,t,h,e,m,a,t,i,c,s"? I get the results pretty fast for that one.

bobbym · 2012-08-30 10:33:20

Hi anonimnystefy;

What settings and what answer did you get?

I use:

11
5
Yes
No

see the first drawing in post #17.

anonimnystefy · 2012-08-30 13:12:51

11
5
No
No

bobbym · 2012-08-30 16:01:55

Hi;

That is not the same problem.

MathsIsFun · 2012-08-30 19:41:48

The calculations are done on your own PC, so results may vary.

And so it is hard for me to write a program that will finish within the "timeout" that is imposed by Flash.

bobbym · 2012-08-30 19:49:14

Hi MathsIsFun;

No problem. It works for the smaller problems that I have tried on it so far.

anonimnystefy · 2012-08-31 00:07:19

Hi bobbym

You are right. It takes much more time and it comes out empty.

Hi MIF

I would suggest that for very large output (more than 10^7 possibilities), you do not show the whole output, just the number of possibilities.

bobbym · 2012-08-31 01:21:53

Hi;

10^7 is a little bit too large. The above problem only has 13000 permutations. Maybe 10^5 is better.

anonimnystefy · 2012-08-31 01:29:27

Either way, it should skip the printing when the number is large.

How did you calculate the number of the possible combinations?

bobbym · 2012-08-31 01:31:46

I didn't. I counted the number of permutations.

anonimnystefy · 2012-08-31 01:39:15

What permutations?

bobbym · 2012-08-31 01:41:29

The problem in post #17 is a permutation.

As you were taught, you try not to work on a problem that you do not already know the answer to. Remember back engineering? You work from the answer to the question, filling in the details.

Normally to do that I would have just counted them up first. But here MIF already does that with his program so you should use what to get the answer?

GF's of course!

anonimnystefy · 2012-08-31 02:13:54

When you choose a number of objects out of a larger set of objects, those can be only combinations or variations, not permutations.

bobbym · 2012-08-31 02:19:49

Did you look at post #17? When order counts we are talking about a permutation.

anonimnystefy · 2012-08-31 02:23:03

No, when order counts, it is a variation.

bobbym · 2012-08-31 02:30:34

Hi;

http://www.askamathematician.com/2010/0 … nt-matter/

You will notice that in this exact type of problem he calls it an arrangement or permutation.

Anyways, it is calculated in the same way.

anonimnystefy · 2012-08-31 02:33:55

Just because he calls it that, doesn't mean it should be called that way.

I can't seem to calculate those using GFs.

bobbym · 2012-08-31 02:39:35

http://en.wikipedia.org/wiki/Permutatio … binatorics

Post #17 is similar to a mississippi problem, which is definitely a permutation.

I can't seem to calculate those using GFs.

Well of course you can not if you call it a variation. There are ogf's for combinations and egf's for permutations.

Math Is Fun Forum

#26 2012-08-30 09:00:53

Re: Combinations and Permutations "Rules"

#27 2012-08-30 09:50:14

Re: Combinations and Permutations "Rules"

#28 2012-08-30 10:07:14

Re: Combinations and Permutations "Rules"

#29 2012-08-30 10:10:39

Re: Combinations and Permutations "Rules"

#30 2012-08-30 10:12:55

Re: Combinations and Permutations "Rules"

#31 2012-08-30 10:18:21

Re: Combinations and Permutations "Rules"

#32 2012-08-30 10:22:35

Re: Combinations and Permutations "Rules"

#33 2012-08-30 10:31:36

Re: Combinations and Permutations "Rules"

#34 2012-08-30 10:33:20

Re: Combinations and Permutations "Rules"

#35 2012-08-30 13:12:51

Re: Combinations and Permutations "Rules"

#36 2012-08-30 16:01:55

Re: Combinations and Permutations "Rules"

#37 2012-08-30 19:41:48

Re: Combinations and Permutations "Rules"

#38 2012-08-30 19:49:14

Re: Combinations and Permutations "Rules"

#39 2012-08-31 00:07:19

Re: Combinations and Permutations "Rules"

#40 2012-08-31 01:21:53

Re: Combinations and Permutations "Rules"

#41 2012-08-31 01:29:27

Re: Combinations and Permutations "Rules"

#42 2012-08-31 01:31:46

Re: Combinations and Permutations "Rules"

#43 2012-08-31 01:39:15

Re: Combinations and Permutations "Rules"

#44 2012-08-31 01:41:29

Re: Combinations and Permutations "Rules"

#45 2012-08-31 02:13:54

Re: Combinations and Permutations "Rules"

#46 2012-08-31 02:19:49

Re: Combinations and Permutations "Rules"

#47 2012-08-31 02:23:03

Re: Combinations and Permutations "Rules"

#48 2012-08-31 02:30:34

Re: Combinations and Permutations "Rules"

#49 2012-08-31 02:33:55

Re: Combinations and Permutations "Rules"

#50 2012-08-31 02:39:35

Re: Combinations and Permutations "Rules"

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