Euler Definition and 387 Threads

  1. G

    Euler equations with Y(1) = 0, Y(2) = 0

    Is it possible for an Euler equation to satisfy the boundary conditions Y(1)=0, Y(2)=0? I have considered the three possibilities, distinct real roots, repeated roots and conjugate complex roots and cannot find any solutions. Are there any other possibilities to consider? Thanks
  2. S

    Euler lagrange equation and Einstein lagrangian

    Dear everyone can anyone help me with the euler lagrange equation which is stated in d'inverno chapter 11? in equation (11.26) it is said that when we use the hilbert-einstein lagrangian we can have: ∂L/(∂g_(ab,cd) )=(g^(-1/2) )[(1/2)(g^ac g^bd+g^ad g^bc )-g^ab g^cd ] haw can we derive...
  3. O

    Deriving Nonrelativistic Euler Equations from Stress Energy Tensor

    Hi, I would like to start from the stress energy tensor for the perfect fluid: T^{\mu\nu}=\begin{pmatrix} \rho c^2 & 0 & 0 & 0\cr 0 & p & 0 & 0\cr 0 & 0 & p & 0\cr 0 & 0 & 0 & p\cr\end{pmatrix} where \rho is the mass density and p is the pressure, and I would like to derive the...
  4. M

    Solve Euler's Equation: x3y'''+15x2y''+61xy'+64y=0

    Given the homogeneous equation: x3y''' + 15x2y'' + 61xy' + 64y = 0 I get 3 solutions which are all -4. Does this mean that the solution for y should be: y = c1x-4 + c2x-4lnx + c3x-4ln2x ?
  5. N

    Euler angles of rotation about x=y=z

    What would be the euler angles of rotation 2pi/3 about the line x=y=z? If something were in the xy plane and it underwent that rotation, would it end up in the yz plane?
  6. Q

    Solving an Example Euler Equation Problem | Understanding the Reduction Process

    Homework Statement This is a problem that the book uses as an example and I've been trying since friday to get the same answer but i have not had any success, i need help :( Well in this problem, F = y(1+(y')^2)^1/2 Homework Equations eulers eqn d/dx(partial(F)/partial(y')) -...
  7. Y

    Understanding the Roots of Euler's Equation and Finding the Second Solution

    I am a self studier, there might be things seems obvious to you guys that are not obvious for me. I have a few questions here, I write down the equation first and present the question in the last part. Please bare with me. Thanks. Eulers equation of 2nd order: L[y]=x^{2} y''+ \alpha xy'+...
  8. J

    Solving Backward Euler with Newton's Method

    Greetings, I am trying to implement backward euler implicit method by Newton-raphson iteration. The differential equation is for a simple planar pendulum. So the function for the pendulum is : (1) angularAcceleration (angle) = ( -gravity/length ) * sin(angle); and the update function for...
  9. K

    Comp Sci Fortran 90 Euler Scheme for Radioactive Decay

    Homework Statement in fortran 90 write a program to using the euler scheme to solve the differential equation for decay of a radioactive substance dx/dt = -j*x solving the equation we get x = e^(-j*t) following info is given 2. Homework Equations and values t0 = 0.0 tF =...
  10. N

    Euler methond and the improved Euler method

    I am confused by both of these. I get what it does, and how it does it, but when using it, somehow I ultimately screw up. Could someone just post a quick description of what to do in conversational English, please? I am pretty sure that would solve this random mental block I have...
  11. J

    Backward Euler / Implicit Integration Implementation

    Hi all, I am trying to implement the backward euler integration (in c++) for the pendulum problem. I have the forward euler implemented, but frankly I don't know where to even start from for the implicit integration. I understand the update expressions for implicit, and of course the...
  12. L

    Finding the Deduction for Euler Number

    Hi, Can anyone show me what´s the deduction for e Euler number ? Thank you
  13. E

    Project Euler - What you've learned

    So I registered on http://projecteuler.net/" and I must say: it's quite addictive! I didn't expect it to be that much fun. I'd like to share what things I've learned from solving the problems: - When solving a problem you get access to a thread. I was impressed how different the...
  14. S

    Project Euler Problem 3: Finding the Largest Prime Factor

    What is the largest prime factor of the number 600851475143 ? My attempt: #include <stdafx.h> int main() { int num1, num2, num3, num4, lrgprime, sum; lrgprime=num2=num4=sum=0; for (num1=2; num1<300425737572; num1++) { num2=600851475143%num1; if (num2==0) { for...
  15. D

    Euler Problem #14: Find Longest Chain <1M

    im trying to do the Euler problem #14 - to determine which starting value under one million produces the longest chain and here's my code in Python Count=[] Count2=[] List=[] def seq(n): if n%2==0: return n/2 else: return 3*n+1 m=1 for i in range(1,1000000): j=i List.append(j) while...
  16. C

    How is the solution for y[n+1] obtained using Euler's forward method?

    Hi all, I'm having trouble understanding a basic concept introduced in one of my lectures. It says that: To solve the DE y(t) + \frac{dy(t)}{dt} = 1 where y(t) = 0, using the Euler (forward) method, we can approximate to: y[n+1] = T + (1-T)y[n] where T is step size and y[0] = 0...
  17. D

    Solution of Euler Differential Equation Using Ansatz Method

    Homework Statement Solve the euler differential equation \x^{2}y^{''}+3xy'-3y=0 \int_X f = \lim\int_X f_n < \infty by making the ansatz [tex]y(x)=cx^{m}[tex], where c and m are constants. The Attempt at a Solution [tex]y(x)0=c^{m}[tex] [tex]y^{'}(x)=cm^{m-1}[tex]...
  18. S

    The Euler formula how was it developed?

    I'm reading a book called The Road to Reality by Roger Penrose, and I'm on the chapter for complex logarithms. What I don't understand is how the identity e\theta i = cos \theta + i sin \theta is found through the use of complex logarithms. I also don't understand how if w = ez, z = log r +...
  19. Z

    What is the Remainder of 2 to the Power of 1000005 Divided by 55?

    Homework Statement i need to obtain the remainder of the divison 2^{1000005} divided by 55 Homework Equations Euler theorem 2^{\phi (55)}=1 mod(55) The Attempt at a Solution my problem is that applying Euler theorem i reach to the conclusion that the remainder is the...
  20. S

    Forward euler equations of motion

    Homework Statement Hi, I'm trying to compute the equations of motion for a car as shown in the attached image. α = steering angle θ = orientation of the car relative to the world coordinate system Say you're given the linear velocity v and the steering angle α. How do you compute...
  21. S

    Forward euler calculations for position and orientation

    Hi, I'm trying to compute the equations of motion for a car as shown in the attached image. α = steering angle θ = orientation of the car relative to the world coordinate system Say you're given the linear velocity v and the steering angle α. How do you compute the position and angle...
  22. N

    [Numerical] Euler Backward method

    Hi, I need to solve the following simple ODE with both the Euler Forward and Euler Backward numerical methods. I also need to answer for which values of T this can still be calculated: y'(t) = \frac{-1}{2y(t)} y(0) = 2 t \in (0, T] Obviously the analytical solution is y(t) = \sqrt{4 - t} So it...
  23. F

    Convert from unit vector to (maybe) special euler angles on a machine tool

    Hello, I am trying to extract the 3 angles from a unit vector to position a part on a 5 axis milling machine: This machine has 3 linear axes (x,y,z), direct coordinate system It has 2 rotary axes: A turns about the x (called 'tilt') C is carried on the A axis (called 'rotary') See...
  24. T

    Calculating Euler Buckling of Open I Beam in 3 Point Bending

    Homework Statement I want to find the euler buckling for a open I beam( middle section like a box) that is subjected to three point bending with a point load on top. I am not so interest in a solution but explanation on how this could be worked out using the euler equation for buckling...
  25. K

    Limits: rate of convergence of Euler

    Homework Statement Prove that the rate of convergence for Euler's method (in solving the problem y'=y) is comparable to 1/n by showing that lim_{n\rightarrow infinity} \frac{e-(1+\frac{1}{n})^n}{1/n}. Homework Equations Hint: Use L'Hopital's Rule If lim x-> infinity f(x)/g(x) is in...
  26. O

    Euler lagrange equation, mechanics,

    Could somebody explain to me how lagrange multipliers works in finding extrema of constrained functions? also, what is calculus of variations and lagrangian mechanics, and can somebody explain to me what the lagrangian function is and the euler-lagrange equation. And, i read something about...
  27. S

    What is the Euler Totient Function for Coprime Numbers?

    Q- Let m and n be coprime. Show that\phi(mn) = \phi(m) * \phi(n). Hint: when does a pair of residues modulo m and n have an inverse.
  28. M

    Can Euler's formula accurately calculate arcsine?

    1. I use Euler formula of arctan to calculate arcsine 2. This equation\arctan x = \frac{x}{1+x^2} \sum_{n=0}^\infty \prod_{k=1}^n \frac{2k x^2}{(2k+1)(1+x^2)}. If I input 0.9999999999, I will not be able to get the expected result. If input = 0.9 then it is pretty correct, but 0.99 is definitely...
  29. S

    Euler Totient Formula for Prime Powers | Help Needed for Homework

    Homework Statement Well, the question is to find a formula for \phi(p^n) where \phi is the Euler's totient, and p is a positive prime. Homework Equations \phi(2^n) well in this case here is what i did, i first took n=1, n=2, n=3, and it looks like \phi(2^n)=2^{n-1} but i am...
  30. P

    Calculating Euler phi function

    How do i comput the euler phi function of a large interger? i know that if p is prime then phi(p)=p-1 and I've found a formula for computing non primes but i don't know how to implement in something like Matlab. Does anyone know how?
  31. P

    MATLAB Compute Euler Phi Function of Large Integer | Matlab Solution

    How do i comput the euler phi function of a large interger? i know that if p is prime then phi(p)=p-1 and I've found a formula for computing non primes but i don't know how to implement in something like Matlab. Does anyone know how?
  32. M

    Prove Euler Identity without using Euler Formula

    Is it possible to prove Euler's identity (e^i*pi = -1) without simply taking it as a special case of Euler's formula (e^i*x = cos(x) + i sin(x))?
  33. A

    Proving n/Φ(n)=2q/q-1: A Proof Using Euler's Totient Function

    Hello, can anyone help with this question? Thank you. Let n even perfect number and q prime. Show that n/Φ(n)=2q/q-1. Φ(n) is the Euler function-totient (the number of positive integers less than or equal to n that are coprime to n) I have tried euler-euclid theorem but could not...
  34. S

    Fortran Why Is My Euler Method in Fortran Not Updating Yn Correctly?

    Euler Method in Fortran - HELP! Using Euler method I want to calculate the equation below, deltat=0.3, 10 times. Problem: When n=1, Yn1(1) is calculated right. But, in the following steps it should assume that Yn(2)=Yn1(1) and the program is assuming Yn(2)=0, as well as Yn(3)=0,...and so on...
  35. M

    Is There a Way to Regularize Euler Products on Primes?

    although is not valid in general (since an Euler product usually converges only when Re(s) >1) \frac{ d \zeta(1/2)}{\zeta (1/2)}= -\sum_{p} log(p)(1-p^{1/2}
  36. Y

    How do I solve for w and p in an incompressible flow using Euler's equation?

    I'm stumped on a HW question that I just can't seem to proceed on. Homework Statement An incompressible ( rho = constant ) flow in 2 dimensions [x = (x,z)], with F = (0,-g), satisfies Euler's equation. For this flow, the velocity is u = (u0,w(x)), where u0 is a constant, with w = 0 on x...
  37. N

    Solving Euler Theorem Doubts with Partial Derivatives

    firstly, all d's i use will mean partial derivative 'do' because i don't have the font installed. sorry :( please help me with these.. u got to use euler theorem 1. if z= xf(y/x) + g(y/x), show that x2(d2z/dx2) + 2xy(d2z/dxdy) + y2(d2z/dy2) =0 2. if z= (xy)/(x-y), PT (d2z/dx2) + 2(d2z/dxdy)...
  38. B

    MATLAB Euler Method in MATLAB: Solving a Double Pendulum

    Hi all Im working on a systems dynamics problem which involves modelling a double pendulum, a chaotic system I have a non linear system of 4 1st order differential equations which I need to solve using numerical methods in MATLAB The methods are ode45, ode23s and euler method Ive...
  39. L

    How Do You Calculate Euler Angles Between Two Versors?

    Dear All, Suppose you have two versors x and y. You would like to calculate the 3 Euler angles between them. How would you do that? You know that x=Ry where R is the rotation matrix (see e..g Goldstein). Now the point is that I know both x and y and want to get phi, theta and psi (no...
  40. P

    Solving Euler Equation for F(K) and U(C) with Initial and Terminal Conditions

    The functions K maps to f(K) and C maps to U(C) are given as: F(K) = aK and U(C) = -C^2 +b here a and b are positive constants. the initial and teriminal conditions with the triminal time T = 1/a are K(0) = K_0 and K_T = K(1/a) here K_0 and K_T are positive constants. Write Euler...
  41. M

    Givens rotations versus Euler angles

    Trying to implement QR decomposition using Givens rotations, I calculate G1 to zero n32 of original matrix A, then G2 to zero n31 of G1 * A, then G2 to zero n21 of G2 * G1 * A. Residual matrix, R = G3 * G2 * G1 * A comes upper triangular as expected, so I believe my code is correct. Looking...
  42. J

    Euler and lagrange frame of reference

    can anybody please clearly explain me the difference between these two frames of reference with few examples. my exames are closing up. please help me.
  43. K

    Validity Using Euler Circles and Truth Tables

    I'm so confused on how to tackle this problem: 1. Truth tables are related to Euler circles. Arguments in the form of Euler circles can be translated into statements using the basic connectives and the negation as follows: Let p be “The object belongs to set A. “Let q be...
  44. M

    Runge-Kutta vs Euler: Solving Two-Dimensional Differential Equation

    Hi, I don't know if this is the right forum to adress, but I will try nevertheless Im solving a simple two-dimensional differential equation: dx/dt = (-y,x) which will give a circle when integrating over time. Now, the problem is that the simple euler scheme seems to be a lot more...
  45. T

    How Did Euler Link Complex Exponentials to Trigonometric Functions?

    In the general DE form, y"+y=0 and where the initial conditions are y(0)=2 and y'(0)=0, Euler realized that y(x)=e^ix+e^ix. How did he know that it's a cosine graph when there's no indication in the equation that any solution is possible? y= c1+c2=2 but y" gives 0.
  46. X

    Does d dividing n imply phi(d) divides phi(n)?

    Prove that if d divides n then phi(d) divides phi(n). Thanks
  47. P

    Using Euler Lagrange in General Relativity

    I'm trying to follow a professor's notes for finding Christoffel symbols for a two-sphere. He gives the following two equations: The Lagrangian for a two sphere:L = \left( \frac{d\theta}{ds} \right)^2 + sin^2\theta \left( \frac{d\phi}{ds} \right)^2 The Euler Lagrange equation: \frac{d}{ds}...
  48. J

    Solving non-linear equations simultaneously with DE's using Euler integration

    I have 15 equations with 15 unknowns describing a dynamic process. I would like to know how I can conbine solving non-linear equations together with ordinary differential equations (1st and 2nd order) simultaneously, without using ode45, but Euler's method.
  49. B

    Drawing Direction Fields for Non-Autonomous Differential Equations

    Direction field Do anybody have a hint for drawing direction field of a non-autonomous differential equation? I mean do I have to calculate as many slopes of points as possible, then draw it? Also, Can I conclude that if we use Euler's Method to estimate a CONCAVE UP/ CONCAVE DOWN...
  50. C

    Euler expansion of double exponential?

    Simple question, I have used the euler expansion to estimate a variable that grows as a single exponential. adapt = Amax * exp(-tau*X); In excerpted form: for (i=1;i<npts; i++) { adapt[i] = adapt[i-1] + (Amax -adapt[i-1]) * dt / tau; } where dt is the step size and tau is...
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