What is Elements: Definition and 1000 Discussions

Éléments is a French bi-monthly magazine launched in September 1973 and associated with the Nouvelle Droite.
With a social and European inspiration, the magazine promotes a critical vision of liberal modernity on topics such as localism, ecology, respect for cultural diversity and the defence of European identity.

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  1. Whovian

    C/C++ C++ array with variable no. of elements?

    #include <iostream> using namespace std; int a; int main() { cin >> a; int c [a]; for (int i = 1;i!=a+1;i++) { c [i] = i; } for (int i = 1;i!=a+1;i++) { cout << c [i] << endl; } return 0; } This compiles and does exactly what it's supposed to. But wait...
  2. Q

    2D Vector Work With Wind and Other Elements

    Homework Statement You are a pilot on an F-16, waiting on a still aircraft carrier. You must fly to another aircraft carrier 1450 at 45* from your position, moving at 56 km/h due east. The wind is blowing from the south (To the north) at 72 km/h. Calculate the heading and air speed needed to...
  3. C

    How do we account for all the elements in the Universe?

    Hi all, New to the forum - first post. I've wondered for a while how all the elements were able to be created given the timeline of the universe. If the solar system is ~5billion years old and the universe is 14 billion years old that means that all of the elements of the solar system...
  4. A

    MHB Elements of a Ring: R Has 64 Elements

    f:R->S is a homomorphism of rings,such that kernel of f has 4 elements and the image of f has 16.How many elements has R? 16=|Im ( f )|=|R/ker f|=|R|/|ker f|=|R|/4=>|R|=4*16=64
  5. K

    Where do the heavier elements come from, such as those found in planets?

    Something similar to this came up in a lecture but it wasn't explained very well. From wikipedia it seems that our sun is made up of 74.9% Hydrogen and 23.8% Helium. The final 1.3% is made up of heavier elements such as oxygen, carbon, neon, and iron. If the the entire solar system condensed...
  6. E

    Relays - Controlling voltage flowing for heater elements to maintain temperature

    So I have a UT130 Temperature Controller turning on and off a heater element through a SSR relay to maintain the temperature of water at a constant temperature. But the problem is that the temperature will still fluctuate making the relay go on and off continuously. I need the water to stay at...
  7. R

    Ring problem: nilpotent elements and units

    Homework Statement Let R be a ring with multiplicative identity. Let u \in R be a unit and let a1, ..., ak be nilpotent elements that commute with each other and with u. To show: u + a1 + ... + ak is a unit. The Attempt at a Solution Need to show that u'(u + a1 + ... + ak)=1 for some u'...
  8. H

    Negative diagonal elements in Incomplete Cholesky Decompostion

    Dear all, I'm facing a problem in performing incomplete Cholesky decomposition of sparse matrices. I use the algorithm which avoids talking square roots, given in here: http://en.wikipedia.org/wiki/Cholesky_decomposition and apply it to sparse matrices by just skipping the zeros ( no...
  9. S

    Number of elements in a ring with identity.

    Homework Statement 1_R=identity in the ring R. /=...not equal Having some issues with this any help will be great: Let R be a ring with identity, such that x^2 = 1_R for all 0_R /= x ,where x belongs to R. How many elements are in R? Homework Equations The Attempt at a Solution...
  10. O

    Maxwell's, integrals, current, elements, delta phi and confusion

    I'm working on an online EECS course, and to be frank some of it is going straight over my head - but at the same time parts of it are far below my current knowledge, so I want to work and stick with it. The speaker is working through proving current and voltage - to arrive at Kirchoff's...
  11. T

    Minimum number of elements to in one set to sum to all in another.

    Is there a name for the concept of trying to find the minimum number of elements from one set of integers that will sum to all elements in another set? Like, for example, with the Pythagorean Theorem, this would be to find the minimum number of elements from the set of all squared integers that...
  12. P

    Step-by-step insertion of elements into a 2-3 tree?

    Homework Statement I'm trying to figure out how to insert elements into a 2-3 tree, based on the tree shown in this image: http://imageshack.us/photo/my-images/851/btreeexercise.gif/ The two elements I need to insert at 197 and 52. 2. The attempt at a solution I'm fairly confident...
  13. A

    MHB Number of elements in a ring with identity.

    1_R=identity in the ring R. /=...not equal Having some issues with this any help will be great: Let R be a ring with identity, such that x_2 = 1_R for all 0_R /= x ,where x belongs to R. How many elements are in R? Thanks
  14. F

    Density matrix elements, momentum basis, second quantization

    Hello everyone, I'm having some trouble, that I was hoping someone here could assist me with. I do hope that I have started the topic in an appropriate subforum - please redirect me otherwise. Specifically, I'm having a hard time understanding the matrix elements of the density matrix...
  15. M

    Can Modern Alchemy Turn Lead into Gold, and What Does the Future Hold?

    Lead AN 82 and gold AN 79 are fairly close to one an other on the Periodic Table - so maybe the alchemists of the middle ages were on to something. In fact it was already done: There are reports that Glenn Seaborg, 1951 Nobel Laureate in Chemistry, succeeded in transmuting a minute quantity of...
  16. E

    How do you count unique elements when multiplying integers from 1 to 1000?

    say you are multiplying integers from 1 to 1000 and you want to count the number of "unique" elements. How would you do that? Is there a closed form expression for that? counting the unique or non-unique elements is the same since we know the total number of elements and can get the unique or...
  17. TrickyDicky

    Light elements abundance in a static toy universe

    As an exercise in cosmology-fiction (I actually got curious about this from an actual cosmology textbook problem), taking into account the stellar nuclear reactions that involve the fusion of hydrogen into helium, what would (roughly) be the proportion (in mass) between Hydrogen and He-4 in a...
  18. K

    Showing two certain sets have no elements in common

    Homework Statement Let x and y be irrational numbers such that x-y is also irrational. Let A={x+r|r is in Q} and B={y+r|r is in Q} Prove that the sets A and B have no elements in common. Homework Equations The Attempt at a Solution Since x and y are in A and B, then...
  19. S

    Infinite Order of Non-Identity Elements

    Homework Statement G is an abelian group with H the subgroup of elements of G with finite order. Prove that every non-identity element in G/H has infinite order. Homework Equations The Attempt at a Solution Suppose gH in G/H has order n. Then (gH)n = gnH so gn is in H. Then there is some m > 0...
  20. F

    How many elements of order 50 are there in this group?

    The group in question is U100, the group of units modulo 100, which, correct me if I'm wrong, is equal to {3, 7, 9, 11, 13, 17, 19, 21, 23, 27, 29, 31, 33, 37, 39, 41, 43, 47, 49, 51, 53, 57, 59, 61, 63, 67, 69, 71, 73, 77, 79, 81, 83, 87, 89, 91, 93, 97, 99}. How many elements are there of...
  21. Biosyn

    Rare Earth Elements: Extracting from Nuclear Waste?

    How are rare Earth elements and minerals extracted from nuclear waste? And I know that some people are saying that there is a low supply of rare Earth elements needed in high tech manufacturing, could that shortage be solved by extracting these rare elements from nuclear waste?
  22. A

    Why the sun didn't absorb heavy elements from early solar system?

    Hi, ive been studying formation of solar system and couldn't find an explanation for why the sun didn't absorb heavy elements from early solar system? why they remained around the sun and formed planets and not get absorbed to the centre? thanks in advance
  23. G

    Missing elements of Grignard reagent reactions

    Homework Statement Find the product of each reaction Homework Equations Butanal (http://www.chemspider.com/Chemical-Structure.256.html?rid=e530204e-5d67-41a8-88e9-fc8e0ffcf41b), reacted first with bromobenzene...
  24. B

    Can a group have repeating elements?

    Can a group, G, have repeating elements? And if so does the order of G include these repeated elements? Thanks!
  25. B

    Group theory, order of a product of two elements

    I search for an 'elementary' proof of this, where results about structure of abelian groups are not used. I've tried a standard way of proving this, but hit a wall. I'm mainly interested if my work on a proof can be expanded to a full solution. Homework Statement Let G be an abelian group...
  26. N

    General truth about elements of a matrix to the n-th power?

    Say we have a matrix P with eigenvalues \lambda_1, \cdots, \lambda_n (possibly some are the same) and P can be diagonalized, then we can always say that the element on the a'th row and b'th column of P^n is equal to P^n(a,b) = \sum_{i = 1}^n \alpha_i \lambda_i^n with \alpha_i independent of n...
  27. T

    Showing Uniqueness of Elements of a Vector Space

    Homework Statement http://img267.imageshack.us/img267/8924/screenshot20120118at121.png The Attempt at a SolutionWe have that X = A + B. To show that X is unique, let two such sums be denoted by X1 X2 such that X1 ≠ X2. We write, X1 = A + B X2 = A + B The equations imply, X1 - A - B = 0 X2...
  28. Z

    Negative off-diagonal elements in density matrix?

    I have a quick question. I've been trying to search for an answer, but I'm probably looking in the wrong places. Is it valid to have negative off-diagonal elements in a density matrix? Thanks!
  29. M

    Group like elements of Universal enveloping algebras

    I'm working with universal enveloping algebras, specifically U(sl(2)). Does anybody know of a nice way of determining what the group like elements are. Of course, one could go a direct route and compare the coproduct Δ(v), v\in U(sl(2)), directly with the desired outcome v\otimesv, but the...
  30. S

    MATLAB Matlab Symbolic toolbox question, 'exp' and vector elements

    I have a piece of code which near its end needs to do the following task: Given a vector V=(log(A),log(B),log(C)) that has been previously generated[I've used 'log' as opposed to ln here because the 'log' function in MATLAB is the natural logarithm], I need to find sum(A,B,C). NOT...
  31. R

    Engineering Why Does a Parallel Circuit Show Different Voltage Readings?

    Homework Statement https://photos-1.dropbox.com/pi/xl/rLbkcUie-3Lbcrb5YgTa73zJKs4agFowWz6uGFoBq7s/38240/1324436400/1241536/ the image seems to be broken, so here is a link http://db.tt/fMwm8TrL I recently picked up a future textbook of mine for something to do over the holidays...
  32. 7

    Is it possible to extract the diagonal elements of a matrix into a vector?

    Is it possible to extract the diagonal elements of a matrix into a vector?? Is it possible to extract the diagonal elements of a matrix into a vector USING ONLY MATRIX MULTIPLICATION? So no element by element multiplication, and no diag commands. (This will eventually be implemented in...
  33. C

    Intro to Algebra, Symmetric group # of elements of order 4 in S6

    Homework Statement How many elements of order 4 are in S6? (symmetric group with order 6) Homework Equations The Attempt at a Solution So, the different forms of elements with order 4 in S6 are (abcd)(ef), (abcd) from there I am sunk on how to calculate. I know there are...
  34. D

    Proving Field Elements Equality: a+b=a+c $\Rightarrow$ b=c

    Homework Statement Prove that if a,b,c are elements of a field. than a+b = a+c implies b=c Homework Equations a + (-a) = 0 0 + a = a The Attempt at a Solution The solution i found is: a+b = a+c a+b+(-a) = a+c+(-a) 0+b = 0+c b=c what I'm not...
  35. B

    Generating Fixed-Point-Free Permutations in Sn

    Homework Statement What subgroup is generated by the fixed-point-free permutations? Homework Equations The Attempt at a Solution I know that the elements that have no fixed points are the ones whose cycle type adds up to n (i.e. all the numbers in {1,...,n} have to be used). I don't know what...
  36. D

    A set A of n elements has n(n-1)/2 subsets of 2 elements

    I would very much like some help to the following problem. Homework Statement Using mathematical induction, prove that a finite set A of n elements has n(n-1)/2 subsets of two elements. The Attempt at a Solution * Base step n=2: 2(2-1)/2= 1 subset of two elements. * Inductive step: assuming...
  37. P

    Exploring the Zeeman Effect in Cadium and Other Elements

    HI I don't understand why cadium or other elements have different zeeman effect because of their electron configiration thanks
  38. B

    Order of Elements: Non-Abelian Group G & Correlation between |a|, |b|, |ab|?

    If a group G is non abelian and a and b in G have orders |a|= n and |b|= m, is there a correlation we can draw between m and n and |ab|?
  39. D

    Fraction of Elements in a group mapped to own inverse by automorphism

    Q: Given a fraction A/B when does there exist a finite group G and an automorphism f s.t. exactly A/B elements of G are mapped to their own inverses (f(a) = a-1? If so how can we find the group? Does anything change if we allow infinite groups? I have a friend who was preparing for an intro...
  40. J

    How could this group possibly have elements of this order?

    Homework Statement It seems to me that every element of Z_45 has order 1, 3, 5, 9, 15, or 45. It seems impossible to have an element of order 2 by Lagrange's Theorem. Is there another way of looking at this problem?
  41. B

    SUBSET K of elements in a group with finite distinct distinct conjugates

    WTS, is that such set is a subgroup. I need to show closure under group operation and inverse. I can do the inverse which is usually the hardest part, but I'm stuck on the grp op. So let a in K and b in K, both have finite distinct conjugates. Their conjugates are in the group too. WTS...
  42. A

    How to find all elements of S4 that satisfy the equation x^4=e?

    well, I'm thinking to answer the question in a generalized way. I want to find all the elements of Sn that satisfy the equation xn=e. well, if m|n and xm=e then xn=e, hence, if we raise x (which is of order m and m divides n) to the exponent n we'll have xn=e. so the answer will be this: S={all...
  43. L

    Proving multiplicative inverses of 2x2 matrix with elements in Z

    So in describing the elements of M2(Z) that have multiplicative inverses, the answer that I keep coming back to is that the only ones are those with determinants of +/- 1, because the determinant would have to be able to divide all elements. I think I've conifrmed this scouring the web, but...
  44. G

    MATLAB MATLAB print individual elements of a matrix

    Consider a matrix A(i,j) What I want to do example: A= [1 2 3; 4 5 6; 7 8 9] I want to to display 1 2 3 4 5 6 7 8 9 I will then save it to a file; I know how to do that. But how do I get MATLAB to display the individual elements sequentially? Thank you. *edit* Nevermind figured it out...
  45. I

    Subsets of a set such that no two have two equal elements

    Homework Statement Given a set of n elements one after another (1,2,...n) Find the minimum n for which there are about 1000 subsets such that every two subsets will have at least 2 elements not in common Homework Equations The Attempt at a Solution I did this problem for 1 element...
  46. D

    The set of all sets which are elements of themselves

    Russell's paradox concerns itself with the set S=\{x|x\notin x\}\;\;\;S\in S ? but it is supposedly solved in ZFC theory. Now, what about the set U=\{y|y\in y\}\;\;\;U\in U ? Is U an element of itself?
  47. B

    Do tuples exist which aren't elements of a cartesian product of sets?

    Do tuples exist which aren't elements of a cartesian product of sets? Can you just write an ordered list of elements which does not necessarily have to be defined in sets? (or does every tuple need to be defined through sets in order for it to rigourously exist in mathematics?)
  48. M

    Matrix elements of the secular determinant for trial functions?

    This is the quantum part for solving wavefunctions of mulit-electron atoms that need to be approximated by the variation method. Specifically we are supposed to differentiate this equation using the quotient rule : E(c1,c2) = [(c1^2*H11 + 2c1c2H12 + c2^2*H22) / (c1^2*S11 + 2c1c2*S12 +...
  49. V

    Operator matrix elements, opposite-parity functions

    Homework Statement For operator H=f(r)γ , where γ=\bigl(\begin{smallmatrix} 0 & I\\ I& 0 \end{smallmatrix}\bigr) , f(r) some even function. Show that matrix element of this operator <\psi_{a}|H|\psi_{b}> is non-vanishing only if ψ_a and ψ_b functions are of the opposite parity...
  50. G

    What causes some elements to be conductive and other element to resist?

    Hi Guys, I am new here I have been programming for some time in C/C++/etc,but my knowledge in physics/chemistry I am currently improving I wanted to know why is the causes that makes some elements resist and some other elements conduct electricity ?
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