Function Definition and 1000 Threads

  1. Andrea Vironda

    I Position of a point as a function of angular position

    Hi, I have this scheme, in which there are 3 segments: - I is coaxial to c axis and free to rotate in the origin. Length d1 - II is coaxial with a axis and free to rotate around c axis. There a fixed angle θ between a and c axis. Length d2 - III is welded to II, it's the PM segment. α is fixed...
  2. S

    B Why do we call function a Rule

    Let's take an example - f: N-->N f(x)= 2x This is called the Rule of the Function. The rule of the function tells us the relationship between the elements (x,f(x))of the ordered pairs in the Function Set. So, if the...
  3. mcastillo356

    Calculators How can I prove my calculator calculates a trigonometric function?

    Considering the measure of angles in radians, that are real numbers, the concept of of trigonometric function spreads to all real numbers. Any real number can be considered as an angle of the first circumference and a ##\mathbb{K}## number of circumferences. We can consider the function...
  4. karush

    MHB Gre.al.12 transformationof a function

    $\tiny{gre.al.12}$ The graph of $y=\left|x-6\right|$ is is the standard $(x,y)$ coordinate plane. Which of the following transformations. when applied to the graph of $y=\left|x\right|$, in the graph of $y=\left|x-6\right|$? a. Translation to the right 6 coordinate units b. Translation to...
  5. H

    I Are electro-magnetic waves the same as the wave function?

    When studying classical mechanics we are told that light is the propogation of electromagnetic waves. This makes perfect sense, as I can imagine these fields behaving this way, and in turn have an associated wave length. When learning about QM, I have heard that the wavelength of a (any)...
  6. Arman777

    Python İmport a python function inside a subfolder

    I have a project folder called Projects and inside that folder I have a file called my_functions.py. Now I have a folder named Project 1 and inside there is another python file called test.pySo it is something like -Projects- my_functions.py -Project 1- test.py Now I...
  7. greg_rack

    Studying non-differentiable points of an irrational function

    I calculated the derivative of this function as: $$\frac{6x^3-4x}{3\sqrt[3]{(x^3-x)^2}}$$ Now, in order to find and later study non-differentiable points, I must find the values which make the argument of the root equal to zero: $$x^3-x=0 \rightarrow x=0 \vee x=\pm 1$$ and then find the left and...
  8. E

    Stability and concavity of the entropy function

    I am struggling to understand Callen's explanation for stability, I understand that the concavity of S(U) must be negative because otherwise we can show that this means that the temperature increases as the internal energy decreases (dT/dU<0) but I cannot understand equation (8.1) which...
  9. S

    B Question about Notation of Function

    In the notation of Function ---> f(x)=y Here f represents the function and x is the variable in the function. we read f(x) as "f of x"or "function of the variable x" what does "function of x " mean that we read ? in this notation what does round brackets ()...
  10. T

    B Question about Planck's Function

    Hi! I have a question about integrating Planck's function of blackbody radiation. Why is it that the area under the blackbody curve will be less than the spectral radiance of individual wavelengths? For example, integrating the Sun's curve over all wavelengths yields a smaller value than the...
  11. Theia

    MHB What is the integral of the Arcus function?

    The exact value of $$\int_{-1}^1 \arcsin (x) \arccos (x) \arctan(x) \mathrm{d} x.$$
  12. E

    MHB Integrating a piecewise function?

    I have to find: g(1)= and g(5)= I have drawn the graph and I am a little unsure where to go from there. I know area is involved somehow but not entirely sure what to do. Any help is appreciated
  13. L Navarro H

    Proof that the exponential function is convex

    I try to proof it but i got stuck right here, i want your opinions Can I get a solution if i continue by this way? or Do I have to take another? and if it is so, what would yo do?
  14. AndreasC

    I Help with an ideal gas canonical ensemble partition function integral

    Where does the volume even come from? Any help would be appreciated!
  15. LCSphysicist

    Find a function satisfying these conditions: f(x)f(f(x)) = 1 and f(2020) = 2019

    Let a continuous function f: R -> R such that f(x)f(f(x)) = 1 and f(2020) = 2019. What is the value of f(2018)? I am having problem with this question. I already tried, through various attempts, to find the function explicitly which satisfy this condition and f(0) different of 0. But it leads...
  16. Jason-Li

    Why Does Increasing G in a Control Loop Cause Vo/Vi to Approach Unity?

    Hi all Physics Forum User, I am again coming to you to ask for help. For the above question I can't make sense of how a larger G will cause Vo/Vi to approach 1. For this I'll call Vo=V and Vi=I As can be seen from the control loop B = A*H and V = B*K hence V = A*H*K Also A = I - C and...
  17. I

    I What type is a polynomial function?

    I often encounter functions called "polynomial" in numerous fields. I don't see an obvious common trait other than that they're usually describing a real-valued continuous function. What aspects are typical or universal or distinct? What structures can be polynomial? Some sources say that...
  18. anemone

    MHB Find Cubic Function & Polynomial of Degree 3

    Find a polynomial of degree 3 with real coefficients such that each of its roots is equal to the square of one root of the polynomial $P(x)=x^3+9x^2+9x+9$.
  19. PaBlo14101066

    Lagrangian function of a double undamped pendulum

    I must find the Lagrangian for an undamped pendulum using the diagram showed below, I've no idea what to do with the second angle φ2 because is measured from the line that joins the two pivot points. The ecuations I must obtain are as follows I get so many different things but I can't reach...
  20. SQUB

    Work function of electrons in a metal

    Hi everyone, I have to solve this homework without having any books where to find the theroical topic or examples, so if you could help me find materials that I can use to understand or you want to try help me understand how to get the solution would be very helpfull. I don't have enough time to...
  21. greg_rack

    Issue calculating the derivative of a rational function

    First, I calculated the derivative of $$D(\sqrt{ax})=\frac{a}{2\sqrt{ax}}$$ Then, by applying the due theorems, I calculated the deriv of the whole function as follows: $$ f'(x)=\frac{\frac{a}{2\sqrt{ax}}(\sqrt{ax}-1)-\sqrt{ax}(\frac{a}{2\sqrt{ax}})}{(\sqrt{ax}-1)^2}=...
  22. D

    Maximize the function with constraints

    I tried parametrizing the domain using spherical coordinates, with theta and phi. I also tried the method of lagrange multipliers, but the substitutions don't easily result in an easy solution. It requires solving five equations for five variables, and no easy way to isolate variables. I think...
  23. T

    B Question on a property of a function which is not a metric

    We have the function d from VxV to another set(not necessarily R) for which the following properties are to be satisfied: i) d(x,y)=0<=>x=y ii)d(x,y)=d(y,x) iii)d(x,z)≤(d2(x,y)+d2(y,z))1/2 ∀ x,y,z ∈ V. What do you say? Would this function have interesting properties on a set and theorems to be...
  24. A

    Domain of definition of the function f(x,y)=x^y

    Good day as said in the title i need the domain of definition of of the function f(x,y)=x^y for me as x^y=expontial (y*ln(x)) so x>0 but the solution said more than that I really don't understand why we consider the case (0,y) in which while should be different from 0, because I will never...
  25. qnach

    A Partition function in number theory and statistical mechanics

    Is the partition function used in number theory and statistical mechanics the same thing?
  26. L

    MHB Is Every Statement Correct in Defining an Onto Function?

    Which of the following statements is equivalent to saying that a function f:A→B is onto? There are 8 options, select all that are correct. x f(A)=B x In the arrow diagram representing f, every point in B has an arrow pointing at it. x ∀y∈B ∃x∈A such that f(x)=y x f−1(B)=A...
  27. LCSphysicist

    What is the purpose of the main function in programming?

    Is the main function really a function, or it is just the name we give to functions like "def Anyfunction: "? I searched about this "main function" and it always appears with the def command. So i am not sure what is the difference between both, if there is.
  28. Rzbs

    A Wannier function in tight-binding model

    What is the relation between Wannier function and LCAO in tight-binding (TB) model? I know in TB we use LCAO but why we have an alternative approch using Wannier function? For example as said in this lecture note: But I don't understand why we use wannier function? Or in general why we use a...
  29. Monoxdifly

    MHB [ASK] Limit of Trigonometry Function

    $$\lim_{x\to0}\frac{sin2x+sin6x+sin10x-sin18x}{3sinx-sin3x=}$$ A. 0 B. 45 C. 54 D. 192 E. 212 Either substituting or using L'Hopital gives $$\frac00$$. Is there any way to simplify it and make the result a real number?
  30. T

    Questions for Electronics Engineering Experts: Oscilloscope, Function Gen & DMM

    Hi experts, I am a student of electronics engineering and a new member. I have few questions related to Oscilloscope, function generator and Digital Multimeter. 1. what does the DC offset on the function generator do? 2. What is the frequency range and type of signals available? 3. What is the...
  31. Frabjous

    I Representations of a delta function

    There are many representations of the delta function. Is there a place/reference that lists AND proves them? I am interested in proofs that would satisfy a physicist not a mathematician.
  32. mingyz0403

    Engineering Graphing Shear and Moment using singuarity function in Excel

    I had found the singuarity function for the shear and moment. I have a hard time calculating the singuarity function and graphing it using excel. Can anyone explain how to calculate singuarity function and graphing it using excel? Many thanks for your help
  33. Swamp Thing

    Mathematica Create real function from symbolic sum formula

    In this code, I define a function of x as the sum of the first x integers. In[7]:= fnSum[x_] := Sum[k, {k, 1, x}] In[8]:= fnSum[x] Out[8]= 1/2 x (1 + x) In[9]:= fnSum[3.5] Out[9]= 6 I would like now to take the symbolic formula underlying fnSum, and use it with real arguments. How can I...
  34. I

    I Quantum Mechanics Wave Function in 3D

    I was wondering if it's possible to plot a wave function that is a function of 3 coordinates, such as (x, y, z). The text my class uses calls this Quantum Mechanics in 3 dimensions, but wouldn't this technically by four dimensions?
  35. U

    I Approximation of a function with another function

    Hi, I am wondering if it is possible to demonstrate that: tends to in the limit of both x and y going to infinity. In this case, it is needed to introduce a measure of the error of the approximation, as the integral of the difference between the two functions? Can this be viewed as a norm...
  36. greg_rack

    Horizontal asymptote of a parametric function

    I'll write my procedure: $$\lim_{x\to\infty}[\frac{(a-2)x^3+x^2}{ax^2+6x+1}]\rightarrow\frac{x(a-2)}{a}\in \mathbb{R}$$ And now, assumed that everything's correct, how do I assign ##a## a value for having that limit finite and ##\in \mathbb{R}##, and so an horizontal asymptote?
  37. anemone

    MHB Can You Meet the Sine Function Challenge?

    Let $a,\,b$ and $c$ be real numbers such that $\sin a+\sin b+\sin c\ge \dfrac{3}{2}$. Prove that $\sin \left(a-\dfrac{\pi}{6}\right)+\sin \left(b-\dfrac{\pi}{6}\right)+\sin \left(c-\dfrac{\pi}{6}\right)\ge 0$.
  38. danielhaish

    I Why quantum wave function collapse is not consider a signal?

    I read about the non-communication theorem and I understand why when changing one practical will not change the other . But suppose that there is two observers that doing the double slit experiment, but using it with two entanglement practicals. observer one should send signal of yes or...
  39. T

    Finding the wave function when given the momentum eigenstate

    For part a, I have the following $$\ket{p_0} = \varphi_{p_0}(x)=\frac{1}{\sqrt{2\pi\hbar}}e^{ip_0x/\hbar}$$ but I am totally lost on how to proceed.
  40. I

    I Complex Conjugate of Wave Function

    I've been studying quantum mechanics this semester in school and have ran into an issue I can't find an answer for. I understand why we take the complex conjugate of the wave function, such as when calculating expectation values. I'm a little confused though as to why we take the complex...
  41. Hamiltonian

    Velocity of a cart moving in the rain as a function of time

    At time t = 0, the mass of the cart is ##M_0## and velocity is ##v_0## in a time interval ##dt## let a mass of ##dm## be added to the cart due to the pouring water and let the reduction in speed be ##dv## ##\lambda = dm/dt## applying conservation of momentum from the ground frame gives $$M_0...
  42. D

    A multivariate function of Toruses - tangent vectors

    Thank you to all those who helped me solve my last question. This week, I've been assigned an interesting problem about toruses. I think I've solved most of this problem on my own, but I'd like to hear a few suggestions for part c. I think this map multiplies tangent vectors by a factor of...
  43. MidgetDwarf

    Is the given function continuous at x= 0? f(x) = {sin(1/x) if x≠0, 1

    I know that the function, g(x)= sin(1/x) has infinite oscillations when the values of x get closer and closer to 0. So its limit does not exist (from graphing it). However, the way that we defined f(x), at x=0, f(x)=1, but f(x)= sin(1/x) on (0,infinity). I have an issue in general showing that...
  44. SchroedingersLion

    A Derivative of norm of function w.r.t real-part of function

    Greetings, suppose we have ##h(u)=\frac{1}{2} \left\|Au-b \right\|_{2}^2## with ##A## a complex matrix and ##b,u## complex vectors of suitable dimensions. Write ##u=u_1 + iu_2## with ##u_1## and ##u_2## as the real and imaginary part of ##u##, respectively. Show that ##\frac {\partial h}...
  45. Theia

    MHB Computing the value of sine function accurately

    Hi all Simple question: How I can compute the value of \(a = \sin \left( 2017 \sqrt[5]{2} \right) \) under following assumptions: No use of advanced numerical libraries is allowed. Only accepted operations are: comparisons, absolute value, addition, subtraction, multiplication and division...
  46. omegax241

    A strange wave function of the Hydrogen atom

    I am trying to solve the following exercise. In a H atom the electron is in the state described by the wave function in spherical coordinates: \psi (r, \theta, \phi) = e^{i \phi}e^{-(r/a)^2(1- \mu\ cos^2\ \theta)} With a and \mu positive real parameters. Tell what are the possible values...
  47. D

    Inverse of a multivariate function

    Any help with this introductory differential geometry HW would be greatly appreciated. My attempt at solving the first problem: y=4x^3-3x has the derivative 12x^2-3, which is 0 when x^2=(1/4). {x^2=(1/4)} is the singular set, and the inverse is defined for everywhere except F({x^2<(1/4)}). the...
  48. A

    MHB Dstermine the equation of function

    The equation of the axis of symmetry of the graph of a quadratic function is x=-1. The graph passes through the points (0,3) and (-3, 9). Determine the equation of the function.
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