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#1 Re: Help Me ! » Curve fitting » 2015-05-21 19:53:30

it steady on 1 after 165, I have examined over 10 points.

#2 Re: Help Me ! » Curve fitting » 2015-05-20 20:34:54

yes it comes from an experiment. least squares is ok.

thank you

#3 Help Me ! » Curve fitting » 2015-05-19 22:21:06

Replies: 5

Hi all;
I need to find a function that fit to all the obtained points. I used MATLAB curve fitting, and found some function. However there is a problem. Most of the proposed function by Matlab rapidly increases or decreases, while my other point which are not engaged in curve fitting are constant and equal to 1. I would be grateful if you suggest me a method to find a most suitable function.

The data is  as below:



Thank you

#4 Re: Help Me ! » writing in formal language » 2015-04-18 01:33:51

this is a engineering work, and may be a little different from pure mathematics. the member of the set is defined by number of the power converter those may have equal output voltage (same value in the set).

another question is that can not we show a set of mod n as ℤn?

#5 Help Me ! » writing in formal language » 2015-04-17 20:37:07

Replies: 2

hi all,
I would like to write following expression using math symbols. since my study branch is not mathematics I am a little confused. I would be grateful if someone help me.

I like to say: set A is subset of integer mod N (N= 2^|A|) and there are at least M member of set A that are smaller than or equal to 2^(M-1)

for example: A={1, 2, 3, 3}. it is subset of integer mod 16 and there are 1 member <= 2^0 , 2 member <= 2^1, 4 member <= 2^2 and 4 member <= 2^3.

how can write this in formal language?

thank you

#6 Re: Help Me ! » Permutation » 2014-04-08 04:54:44

at least one 1 has to be in series because if it not be, I haven't any subset that its value is 1. this is general.
but 6 is for this specific example (x=9, N=4), because if 6 is in set all other member have to be 1 (minimum value). but in this situation I haven't any subset that add up to 4 and 5.

if x was 12 then 6 could be in series like (1,2,3,6).

I think if we could find a relationship for determining maximum value for each problem using N and X we could find the number of sets that satisfy the mentioned conditions.
Am I right?

#7 Re: Help Me ! » Permutation » 2014-04-08 04:38:34

yes, the list is ok! just the sets that haven't any 1 and sets that have 6 have to be obliterate.
(6 1 1 1), (1 6 1 1), (1 1 6 1), (1 1 1 6), (2 3 2 2), (2 2 3 2), (2 2 2 3), (3 2 2 2) have to be obliterated.
I like a formula by having X and N, the number of sets can be obtained. it it obvious that at least one of rooms has to be 1. if we can find a rule for maximum number we may be able to find a  formula.
the highest number for this example is 5. it has relationship with N and X. I am trying to develop a rule for maximum number. I think after that we could develop a rule for obtaining the number of sets.

#8 Re: Help Me ! » Permutation » 2014-04-08 04:10:30

we can generate ,but we cannot generate 4 and 5 of this set 6,1,1,1
we cannot generate 1 of subsets that haven't any 1 like 2,2,3,2

#9 Re: Help Me ! » Permutation » 2014-04-08 03:55:19

sorry, I write it vague.
let me clarify:
I have X and N number of rooms
here are the conditions:
summation of all N number have to be X
and all integer number less than X ([1 X-1]) should be obtained using at least one subset of those numbers.
I can obtain 1 of any series that have at least one 1 in that.

#10 Re: Help Me ! » Permutation » 2014-04-08 02:15:13

there is a condition all numbers up to x=9 could be obtained using the series member but: we cannot generate 4 using 6,1,1,1 or I cannot generate 1 using 2,2,3,2...
some members have to be obliterated.
according to above condition at least one room has to be 1.

Thank you for taking time to help me. smile

#11 Re: Help Me ! » Permutation » 2014-04-07 07:36:49

I have modified the question. I have missed some information sorry.
all natural numbers can be used. gust there are 2 rules the numbers have to add  up to X and all smaller number [1,X-1] could be obtained by adding some of numbers in series. to fulfill this I think the largest number have to be at max first integer number larger than X/2 for X=9-->largest number 5.

#12 Help Me ! » Permutation » 2014-04-07 06:50:26

Replies: 13

I have a number named X and N number of empty rooms. in how many ways I can fill this room to have X? all rooms have to be filled and all smaller number of N should be obtained by addin some of these numbers. and I know x is greater than N. is there any formula?
Example X=9 and N=4 there are the possibilities:
1,1,3,4; 1,1,4,3; 1,3,1,4; 1,3,4,1; 1,4,1,3; 1,4,3,1; 1,2,24; 2,2,1,4; 2,2,4,1; 4,2,2,1; 1,1,2,5;1,1,5,2; 5,1,1,2; 5,1,2,1; 2,1,1,5; 2,1,5,1; 2,5,1,1; 5,2,1,1,

thank you:)

#13 Re: Help Me ! » how many possibility exist? (discrete mathematics) » 2014-04-06 06:24:05

thank you for your help I hadn't known about generating functions. I have find some text on net. it will be my fortune if you answer my question probable may rise after reading them.

thank you

#14 Re: Help Me ! » how many possibility exist? (discrete mathematics) » 2014-04-06 05:55:24

I dealt with it too much and really exhausted. could you introduce some useful resources that provide me some information to solve this problem?

Thank you

#15 Re: Help Me ! » how many possibility exist? (discrete mathematics) » 2014-03-21 00:48:05

the order of number in the choice doesn't count. for example in first example where the set was A= {1, 2 ,4 ,5} and the X=6 there are 2 possible ways (2+4) and (5+1). the transposed answer doesn't count as new way. it means (4+2) and (2+4) counts just 1 way.
but if there was another 4 in series A={1,2,4,4,5} there were 3 possible ways.(1+5), (2+4(1st)), (2+4(2nd)

thank you for your help smile

#16 Re: Help Me ! » how many possibility exist? (discrete mathematics) » 2014-03-20 03:02:37

exactly equal.

just I know X is never greater than summation of all members of the set.

#17 Re: Help Me ! » how many possibility exist? (discrete mathematics) » 2014-03-20 02:56:52

yes, how ever their value are identical but their position in the set is important.

#18 Re: Help Me ! » how many possibility exist? (discrete mathematics) » 2014-03-20 02:46:04

it is important which 1 takes part in building 3. {1st , 2nd, 3rd}, {2nd, 3rd, 4rt}, {1st, 2nd, 4th}, {1st, 3rd, 4th}

#19 Re: Help Me ! » how many possibility exist? (discrete mathematics) » 2014-03-20 02:33:20

lets explain it from beginning. it has been confusing. smile
I have a set of numbers named A, and it has at least 4 numbers. I also have a number (lets call it  X).
X is always smaller or equal to summation of A members.
I like to know how many ways exist to build X from A members.
when all member of A are identical it is easy for example A={1, 1, 1, 1} and X=3 the number of possible ways can be calculated by 4!/(3! 1!) = 4 ways.
is there any way to formulate this for sets that have not identical members for example A={ 1, 2, 3, 7, 9...}?

#20 Re: Help Me ! » how many possibility exist? (discrete mathematics) » 2014-03-19 23:40:45

I'll be grateful if you provide some information about the method.

it is impossible to make 6 form {1, 1, 1, 1}; in second example the desired number was 2.
for example if series is: 1, 1, 1, 1 and <the number is 2> the number of possible ways is 4!/(2! * (4-2)!)
the 6 was for first example.
excuse me for my bad English.

thank you for your reply

#21 Help Me ! » how many possibility exist? (discrete mathematics) » 2014-03-19 07:55:27

Replies: 18

Hi all,
I have a series of number and a single number. Is there any way to find out how many exist to build single number by summation of series members?
for example, suppose the series is: 1, 2, 4, 5
and the single number is 6 there are two ways (2+4) and (5+1)

it is easy when the numbers in series are identical.
for example if series is: 1, 1, 1, 1 and the number is 2 the number of possible ways is 4!/(2! * (4-2)!)
but I like to have a general way by which the possible ways can be calculated even by existing a series with different numbers.

Thank you in advance for your help:)

#22 Re: Help Me ! » Picking a number of a set of numbers (discrete mathematics) » 2014-01-22 04:12:53

I looked at banker's sequence. don't you think that my method is more efficient than that method?
in banker's sequence all possibilities are checked but I think my method reach to answer very soon.
please let me know your idea

#23 Re: Help Me ! » Picking a number of a set of numbers (discrete mathematics) » 2014-01-22 02:49:00

bobbym wrote:


I am able to write a algorithm that maps binary numbers to a subset, very efficiently. the problem is somewhat different. faint

#24 Re: Help Me ! » Picking a number of a set of numbers (discrete mathematics) » 2014-01-21 22:33:25

I have found a way but it's too time consuming.
lets explain it by an example. our digit is {1,2,3,4,5} and in 3-digit category I like to find 9th number.
we now the smallest member of each category is a number with 1 in highest value digit and the lower digits values increment by 1 for example first member of 2-digit category is 12 and first member of 3-digit category is 123. Knowing this lets start solving the problem.
add the sequence number-1 to first digit; if it becomes more than number of our set numbers add 1 to first and second digit. do result minus 6. repeat this till the result become 0. In adding procedure treat the digits based on its location for example first digit is based on 5 and when it becomes 6 it overflows, the second digit is based on 4 and so on
back to example:
first digit is 3 + 8 = 11 -6 = 5. the number becomes 123+011=134
first digit is 4 + 5= 9 -6 = 3 . the number becomes 134+011=145
first digit is 5 + 3= 8 -6 = 2 . the number becomes 145+011=234
first digit is 4 + 2= 6 -6 = 0 . the number becomes 234+011=245

and yes the 9th number is 245
3-digit: 123, 124, 125, 134, 135, 145, 234, 235, 245, 345
I have checked with another conditions and set with higher number of figures and it is ok but in set with high number of members when I look for a number at the end of the category it becomes cumbersome. is there any better solution?

Dear Bobbym, I am able to program by Fortran and C++. I will check Banker's sequence

#25 Re: Help Me ! » Picking a number of a set of numbers (discrete mathematics) » 2014-01-21 21:58:44

location number 4 belongs to example I explain in post #3
in example of post #5, the location is 6 and the category is 6.
about last post, we don't know the number, we just know the category and the number location in that category. an we like to find the number according to this information.
our categories are always consist of all possible numbers not a subset for example 2-digit category: 2-digit = {12, 13, 14, 15, 23, 24, 25, 34, 35, 45}
furthermore the figures always start from 1 and are successive for example {1,2,3} we never have {2,3,4} or {1,3,4}

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