Questions tagged [linearization]
On the many different ways to turn non-linear systems of equations into linear ones.
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divide complex finction in to multiple linear functions
im programing a small controler an have to use sqrt but the controler doesnt suport it . the controler have what they call a 24 point linearization wich means that you chose 24 x and y positions and ...
2
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0answers
19 views
What are hydrodynamic and non-hydrodynamic modes in the Navier-Stokes equations and how do they relate to stability?
I'm new here. I have been reading articles on Navier-Stokes equation and the stability analysis by studying different modes. However I am still confused by what is meant by modes as in the context of ...
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0answers
9 views
dealing with an asymptote in derivative
I'm trying to get a linearized model for a physical system, but I've got an asymptote in the linearized equation that I don't know how to deal with.
I have Bernoulli's equation
$P_o = P + 1/2\rho v^2$...
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0answers
18 views
Linearization along “trajectory of fixed points” v.s. “arbitrary trajectory”
I am reading a lecture and it says:
Consider the continuous nonlinear system: $$\dot{x}(t)=f(x(t)), \, x\in \mathbb{R}^n.$$
Linearize along arbitrary trajectory: $\bar{x}(t):[0,t] \rightarrow \...
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1answer
21 views
Linearization of $a(x^b)(e^{cx})$
I'm working on an assignment and I need to solve the equation $y=a\times(x^b)\times(e^{cx})$.
We're given an array of values for $x$ and their corresponding $y$. We need to figure out $a$, $b$, and $...
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2answers
36 views
tracking error state space, non-linear control example
I am trying to understand an example from [1]. In detail I do not understand how the equation for the dynamic of the tracking error is chosen. I am not a mathematician so please forgive me if I may ...
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1answer
89 views
linearization of minimum function
I need to be advised in linear programming design. I have spent on this issue some time, I have reached my goal partially, but I am blocked by my lack of knowledge in some areas to go further.
Namely, ...
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98 views
Linearization using Taylor series
I'm trying to understand this approximation:
$x \sqrt{\bigg(1+\alpha\Big(\frac{y}{x}-1\Big)\bigg)\bigg/\bigg(1+\alpha\Big(\frac{x}{y}-1\Big)\bigg)} \approx x\bigg(1+\frac{\alpha}{2}\Big(\frac{y}{x}-1-...
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2answers
27 views
(Possibly light question) Data linearization in curve fitting
I was studying curve fitting in numerical methods and met an approximation curve of the form $y=\frac{x}{A+Bx}$. We were supposed to linearize this curve before applying the least square method, but ...
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31 views
Linearization of nonlinear dynamic system
I am reading the following paper:
ergodic theory of chaos and strange attractors, by J.-P. Eckmann (can be easily downloaded)
My question is around equation (1.7)...
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1answer
23 views
Linearising an Equation to the Form y=mx+c
I have been working on some data analysis stuff and I have to linearise this equation so I can plot it as a straight line with form y=mx+c
$$T=2\pi\sqrt{\frac{(k^2 + h^2)}{gh}}$$
Where, T will be ...
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1answer
33 views
Linearizing the following equation
I'm working through a section in a book I'm reading about delay differential equations (Semi-discretization for time delay systems, Springer), and the authors are discussing the following equation
$$\...
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0answers
24 views
Linearizing squareroot equation with x in both numerator and denominator
I am having trouble linearizing the following equation in order to find the relationship of y and x.
$$y=\sqrt{\frac{x*6}{x+0.5}}$$
I was thinking about converting the equation above into the standard ...
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0answers
16 views
Linearization of two binary variables with multiple indexes
At the moment I'm working on a scheduling problem and I'm trying to linearize the following constraint:
$\sum_{k \in K} (s_{j,t} * y_{i,j,k,t} + \sum_{t \in range(t, t+p_j)} \sum_{jj \in J\j} y_{i,jj,...
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41 views
Application of Lyapounov's Theorem
I have the following exercise to fullfill:
Given the system of differential equations $x'=f(x)=-\nabla{g}$ , where $x(t)\in\Bbb{R^3}$ and $g$ is $C^1$ and $f(0)=0$ and $0$ is a total maximum for $g$,...
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60 views
Linear approximation of $3$ variable function and its maximum error?
I've got a problem which asks me to find linear approximation of multi-variable function and its maximum error.
Here's the problem :
By about how much will
$$g(x,y,z)=x+x\cos(z)-y\sin(z)+y$$
...
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1answer
29 views
Linearization of a function: can someone explain me this last step?
I'm studying a linearization of a differential equation. $x(t)$ and $r(t)$ are really small signals and G, K, B and M are constants. I understand everything until I reach
$$ \frac{d^2x(t)}{dt^2}=G+\...
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1answer
30 views
linearization of constraints
I am dealing with an optimization model where my binary variables xi have to follow this type of constraint (in the attached link):
...
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1answer
23 views
Linearization of Autonomous Equations
Consider $y'=y(y-50)(y-100)$
(a) Let $y_e$ be the stable equilibrium solution and let $u=y-y_e$, rewrite the equation as a differential equation for $u$.
$y_e=50, u=y-50, u'=(u-50)(u)(u+50)$
(b) ...
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26 views
linearizing dynamics about non fixed point for LQR implementation.
I am trying to implement LQR control for the cart pole system. I am curious if I can maintain a constant non-zero pole angle. So, I need to linearize my dynamics about my goal state. I know we can use ...
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27 views
Linearization between two ranges
We are currently trying to solve a problem where the input is range of variables x and y.
y $\in$ {min, max}.
x $\in$ {0, 255}
min & max are integers of range $\{-2^{32}, 2^{32} \}$
Need to ...
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0answers
33 views
Determining the original, unapproximated form of a rotation vector
a bit of an odd one here:
I'm reading a paper that supposedly rotates a basis in a symmetric way, using two scalar rotation quantities, $\theta_1$ and $\theta_2$. The idea, I believe, is for each ...
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53 views
Carleman matrix of multivariable functions - Carleman tensor?
Recently I learned about a matrix called
Carleman matrix. It is a matrix used to represent function iteration with matrix multiplying.
Carleman linearization is a technique used to embed a finite
...
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1answer
241 views
How to solve binary nonlinear programming problems?
I have written binary nonlinear programming problem:
Now I want to solve this problem. My decision variables are $x_{i,j}, y_{i,j}$ and $z_{i,j}$. The other terms are constants. N=30 and K=4.
I ...
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1answer
61 views
How do I linearise the rational function to analyze the critical points?
For the system $$\frac{dx}{dt}=\frac{3xy}{1+x^2+y^2}-\frac{1+x^2}{1+y^2}\\\frac{dy}{dt}=x^2-y^2,$$ the point $\begin{pmatrix}1\\1\end{pmatrix}$ is
A. an unstable node
B. a stable node
C....
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1answer
93 views
Linearizing two variable function
I have another linearization question similar to the one in here. This time, I have got two variables in my equation and I am in search of an "$A+B\rho$" or possibly "$A+B\rho+C\theta$" approximation. ...
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40 views
how I can linearize or simplify these complicated and non-linear constraints?
I have some constraints which are in the form $$ \dfrac{x_{1}-x_{2}+x_{3}+\cdots+x_{n}}{(x_{i}-x_{j})^{2}+\cdots+(x_{l}-x_{k})^{2}}+\cdots+\dfrac{x_{1}+x_{2}-x_{3}+\cdots+x_{n}}{(x_{j}-x_{i})^{2}+\...
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3answers
93 views
Linear Approximation of x/ (1-x)
I am trying to linearize the following function, but, having difficulties.
Let,
$x = \frac{l}{m},$
where $l,m \in R^+$ and $l<m$
Assume $l$ is a variable, while, $m$ is a constant (parameter), ...
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1answer
54 views
Linearized Pitot system
I am trying to create a linearized model of a compressible pitot tube system with altitude $h$ as the input and velocity as the output.
When I take the derivative and try and linearize around a point ...
3
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1answer
127 views
Linearization of differential system of equation
I would like to ask if I understand correctly the process of linearization for analyzing critical points.
I was given differential equation:
$\dot x = xy+1$
$\dot y = x+xy$
And my task was to ...
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0answers
73 views
Linearization of nonlinear Schrodinger equation
Picture below is from the 56th page of
Lyapunov stability of ground states of nonlinear dispersive evolution equations. The nonlinear Schrodinger equation (NLS) is
$$
i\phi_t(x,t)+\Delta \phi(x,t)+ ...
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143 views
About linearization around an equilibrium point
Consider the following non-linear differential equation
$$\label{star}
\dot{x}(t) = f(x(t))+g(x(t),u(t)), \quad t\ge 0, \ x(0)=x_0\in\mathbb{R},\tag{$\star$}
$$
where $f(\cdot)$ and $g(\cdot)$ are ...
2
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1answer
228 views
LQR Robotic Arm
I have a robotic arm model in Simulink and I'd like to control the position of the end-effector such that it follows a given trajectory. This is done by inputting joint angles and comparing the output ...
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0answers
44 views
(Checking) derivatives of determinant, cofactor, trace
I'm considering an $n\times n$ matrix $T_\epsilon$ such that there exists a unique inverse for $\epsilon \in (-\delta,\delta)$ for some $\delta > 0$. I'm trying to check whether I've correctly ...
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1answer
26 views
Properties of matrix $T_\epsilon$ such that there exists a unique inverse for $\epsilon \in (-\delta,\delta)$
I'm considering an $n\times n$ matrix $T_\epsilon$ such that there exists a unique inverse for $\epsilon \in (-\delta,\delta)$ for some $\delta > 0$. I'm trying to determine several quantities of ...
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4answers
525 views
Newtons method for finding reciprocal
Define a function 1 which is $f_1(x)=a-1/x$
and function 2 which is $f_2(x)=1-ax $
If I set both to zero I am looking for when $x=1/a$ as the root using Newtons method.
When I do this I get two ...
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0answers
37 views
How to linearize this function around a working point?
How can I linearize the following function, where my variables are $\phi_d$, $\dot{\phi_d}$ and $\dot{L}_1$:
$\dot{L}_1=\frac{1}{2\sqrt{(l_d\cos{\phi_d}-x_Q)^2+(l_d\sin{\phi_d}-x_Q)^2-R_2^2}}\small(2(...
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0answers
27 views
If $ \|G(x+ty)\|<\|G(x)\| $, is then $ \|G(x) + tG'(x)[y]\| <\|G(x)\| $?
It seems intuitive that given a $ C^1 $ function $ f : \mathbb R \to \mathbb R $, where
for some $ t_0 > 0 $ we have $ |f(x+t)| < |f(x)| $ for all $ t \in (0,t_0) $, and
$ f'(x) \neq 0 $,
...
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0answers
24 views
Similarity in the temperature coefficient of resistivity and coefficient of linear (length) expansion
This was posted on physics stackexchange, https://physics.stackexchange.com/questions/390785/why-change-in-resistivity-is-proportional-to-the-original-resistivity? , but got downvotes and close votes. ...
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1answer
288 views
Stability of Euler's Method for non-linear ODE
Consider the ODE
$$y'(t) = \lambda y(t), \quad y(t_0) =y_0.$$
Euler's method $y_{i+1}=y_i+h\lambda y_i $ is stable (meaning that the solution decays or stays constant as $ i \to \infty$) provided that ...
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1answer
2k views
Linearizing Logarithmic Function
I have a given set of data points (y,x) with uncertainties.
When I plot those points on a graph, the trendline appears to follow the equation y = c + a*ln(x).
I want to be able to find the ...
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1answer
66 views
Finding contstant in remainder term for linearization of $exp(x)$
I've managed to find the remainder term for the linearization of $\exp(x)$ about $x=0$ in Lagrange form:
$$
R_1(x)=\exp(θ_Lx)\frac 12x^2 \text{ ,where } θ_L∈[0,1].
$$
My question is how would I ...
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1answer
258 views
Product and Quotient Rule proof using linearisation
So I've recently been introduced to the concept of linearization and now I'm beginning to apply this concept to prove certain differenation rules. I've managed to prove the chain rule so far, but I ...
3
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1answer
134 views
What is the significance of the linearization of a non-linear PDE?
This may be too general a question so please let me know if I need to make it more specific.
I am a first year graduate student in PDEs, and as such have not had much exposure to non-linear PDEs. I ...
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2answers
132 views
Taylor approximation with 2 variables, not sure how to solve this
This is the problem I'm trying to solve:
Let $f(x,y)=ay+sin(bx)+c$. Evaluate the Taylor polynomial at $P(0,0)$ and find the values for $a$, $b$ and $c$ if $P(x,y)=-1+2x-y$
I do know the ...
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1answer
1k views
How to linearize a constraint including product of two binary variables in summation with different indexes?
I am trying to linearize the following two expressions:
$\sum_{k=1}^K \sum_{t=1}^T\sum_{h=1}^W x_{ijkt} a_{hjt} =\sum_{k=1}^K \sum_{t=1}^T x_{ijkt} k , i\in N, j \in M$
$\sum_{k=1}^K \sum_{t=p_{ijk}...
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1answer
120 views
Show that $L(x,y)=ax^2+by^2$ is a Lyapunov function for the equilibrium at the origin
I am looking at past paper questions and I'm a little stuck on this one.
I have the following system of ODEs:
$\dot{x}=(\epsilon x+2y)(x+1)$
$\dot{y}=(-x+\epsilon y)(x+1)$
where $\...
3
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0answers
38 views
A function that turns a power to a product/sum?
I just recently started learning about the logarithm functions, and its concept is quite amazing (f(x.y)=f(x)+f(y)).
Now I'm asking for a similar function but instead of x.y ; we use ...
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1answer
77 views
What were the steps in the linearization of the following equation?
I'm verifying a linear form of an equation, i.e.
I can't find how the equation 6 leads to the equation 7
3
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1answer
372 views
Stationary points and linearisation of non-linear system
So, the problem is:
Find and discuss the behavior of the stationary points of the system :
$$ x'=-y+x\cdot (x^2+y^2)\cdot \sin\sqrt{x^2+y^2} =f(x,y)$$
$$ y'=x+y\cdot (x^2+y^2)\cdot \sin\...
