Questions tagged [linearization]
On the many different ways to turn non-linear systems of equations into linear ones.
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20 views
How to linearise $W=min(X1, X2, X3)$?
How to linearize $W=\min(X_1, X_2, X_3)$ if
\begin{eqnarray}
X_1 = 3y_1 + y_2 + y_3,\\
X_2 = 2y_1 + 5y_2 + 2y_3, \\
X_3 = y_2+7y_3.
\end{eqnarray}
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0answers
20 views
Linearize the following differential equation. [closed]
enter image description here
Question 2 is where I am finding the difficulty.
If theta is small can I set $\cos\theta = \frac{1- \theta^2}{2}$
and would this mean that my linearization is equal to ...
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0answers
40 views
PDE Linearization
I'm trying to linearize the following PDE:$$\frac{\sigma_I}{r} \frac{\partial}{\partial r} \left(r \frac{\partial z(r,t)}{\partial r} \right)=\rho_D gz(r,t)+\rho_T\left(\frac{\partial z(r,t)}{\partial ...
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2answers
31 views
tracking error state space, non-linear control example
I am trying to understand an example from [1]. In detail I do not understand how the equation for the dynamic of the tracking error is chosen. I am not a mathematician so please forgive me if I may ...
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1answer
63 views
linearization of minimum function
I need to be advised in linear programming design. I have spent on this issue some time, I have reached my goal partially, but I am blocked by my lack of knowledge in some areas to go further.
Namely, ...
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0answers
51 views
Linearization using Taylor series
I'm trying to understand this approximation:
$x \sqrt{\bigg(1+\alpha\Big(\frac{y}{x}-1\Big)\bigg)\bigg/\bigg(1+\alpha\Big(\frac{x}{y}-1\Big)\bigg)} \approx x\bigg(1+\frac{\alpha}{2}\Big(\frac{y}{x}-1-...
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2answers
25 views
(Possibly light question) Data linearization in curve fitting
I was studying curve fitting in numerical methods and met an approximation curve of the form $y=\frac{x}{A+Bx}$. We were supposed to linearize this curve before applying the least square method, but ...
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28 views
Linearization of nonlinear dynamic system
I am reading the following paper:
ergodic theory of chaos and strange attractors, by J.-P. Eckmann (can be easily downloaded)
My question is around equation (1.7)...
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1answer
19 views
Linearising an Equation to the Form y=mx+c
I have been working on some data analysis stuff and I have to linearise this equation so I can plot it as a straight line with form y=mx+c
$$T=2\pi\sqrt{\frac{(k^2 + h^2)}{gh}}$$
Where, T will be ...
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1answer
29 views
Linearizing the following equation
I'm working through a section in a book I'm reading about delay differential equations (Semi-discretization for time delay systems, Springer), and the authors are discussing the following equation
$$\...
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0answers
22 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
13 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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0answers
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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0answers
37 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
28 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
27 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
15 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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0answers
22 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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0answers
22 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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0answers
44 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
150 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
60 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,$$ the point $\begin{pmatrix}1\\1\end{pmatrix}$ is
A. an unstable node
B. a stable node
C....
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1answer
63 views
Linearizing two variable function
I have another linearization question similar to the one in here. This time, I have got two variables in my equation and I am in search of an "$A+B\rho$" or possibly "$A+B\rho+C\theta$" approximation. ...
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0answers
39 views
how I can linearize or simplify these complicated and non-linear constraints?
I have some constraints which are in the form $$ \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), ...
2
votes
1answer
50 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
votes
1answer
116 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
62 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
$$
i\phi_t(x,t)+\Delta \phi(x,t)+ ...
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0answers
125 views
About linearization around an equilibrium point
Consider the following non-linear differential equation
$$\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
170 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
40 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
23 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
409 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
57 views
How to linearize a system of ordinary differential equations, ODEs, around a periodic solution (using numerical methods)?
I am trying to linearize the thermal analysis of a spacecraft model with N nodes over M working points in one orbit.
The non-linear equation is given by the following system of first order ODEs, In ...
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0answers
33 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
226 views
Stability of Euler's Method for non-linear ODE
Consider the ODE
$$y'(t) = \lambda y(t), \quad y(t_0) =y_0.$$
Euler's method $y_{i+1}=y_i+h\lambda y_i $ is stable (meaning that the solution decays or stays constant as $ i \to \infty$) provided that ...
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1answer
1k views
Linearizing Logarithmic Function
I have a given set of data points (y,x) with uncertainties.
When I plot those points on a graph, the trendline appears to follow the equation y = c + a*ln(x).
I want to be able to find the ...
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1answer
63 views
Finding contstant in remainder term for linearization of $exp(x)$
I've managed to find the remainder term for the linearization of $\exp(x)$ about $x=0$ in Lagrange form:
$$
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
236 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
121 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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vote
2answers
100 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
94 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
69 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
324 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\...
2
votes
2answers
271 views
Linearization of Differential Equation
Find a linearization of the differential equation for $x$ near $0$.
$$x''(t) + x(t) e^{0.05x} = 0$$
Not sure what to do here. My book isn't any help either..
Any help would be appreciated :)
