MATLAB is a high-level language and interactive programming environment for numerical computation and visualization developed by MathWorks. MATLAB can be used when performing tasks such as signal processing and communications, image and video processing, computational finance, and computational ... ...

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88 views

analytic/euler/runge kutta solutions comparison problem

i've been trying to solve 1st order differential equations with dsolve, euler andy runge kutta methods and compare them on graphics. for simplification, dy means dy/dx: first equation is y' = ...
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1answer
142 views

How to find the zeros of an integral?

I am having trouble finding the roots of an integral. For example $F(c)=\int_a^b{(x^2-c^2)}dx$ for some finite interval $[a,b]$. The problem is that I am trying to do this using numerical analysis. ...
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1answer
57 views

Matlab help to construct matrices with specified rank and such that each eigenvalue is real

I am reading this paper, where at page $68$, section 3.3 (numerical examples for the Drazin inverse), the randomly generated matrix with specified rank and with the property that each eigenvalue is ...
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1answer
57 views

Linear Algebra Matlab matrix loop? [duplicate]

I'm new to both linear algebra and Matlab, so naturally I'm probably asking an obvious question. If someone could attempt to explain to me in layman's terms how to go about answering this question in ...
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0answers
72 views

Discretization of a convolution integral for constrained optimization problem

I'm working on a constrained optimization problem in which an unknown forcing function, $u(\eta)$, is in the integrand of a convolution integral. To find an optimal shape for $u(\eta)$, the integral ...
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1answer
51 views

Hand calculation of magnitude of transfer function doesn't equal what MATLAB says…

I have a simple transfer function, given by: $$\frac{140,000}{s(s+100)}$$ I'm attempting to calculate the magnitude at $\omega$ = 100 rad/s. So I plug in, I get $\frac{140,000}{20,000}$ = 7 Then I ...
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1answer
138 views

Random sampling using Metropolis vs. Accept-Reject

I'm working on a project comparing the accept-reject (von Neumann) and Metropolis methods of sampling. I'm generating a sample of size $N$ from a normal distribution $N(1,(\frac{1}{2})^2)$. What I ...
22
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3answers
2k views

Matlab wrong cube root

How can I get MATLAB to calculate $(-1)^{1/3}$ as $-1$? Why is it giving me $0.5000 + 0.8660i$ as solution? I have same problem with $({-1\over0.1690})^{1/3}$ which should be negative.
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1answer
75 views

Incorrect indefinite integral on MATLAB?

any ideas why matlab is giving me an incorrect answer here? 1 set of commands syms x L N2 N2 = 6*x/L^2 - 2/L^2 N2 = (6*x)/L^2 - 2/L^2 expand(int(N2*N2)) ans = ...
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1answer
41 views

How to Estimate the mean and covariances for all classes from training set?

A training set of 2000 samples ( value :2000 * 2 ) named training_set. how can i estimate the mean and covariances for all classes from training set. already tried mean and cov function.but every time ...
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1answer
1k views

How to split a dataset in test and training set?

How can I split a data set in training and test data set after creating a data set named first_data (contains 3000 samples) in MATLAB? I want to split $2000$ samples as training and $1000$ ...
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1answer
242 views

Not able to use fzero function in Matlab

I am new to Matlab. I am trying to solve a non-linear equation using this inbuilt Matlab function called fzero() but it's not giving me the results. The main file ...
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0answers
988 views

Coupled Differential equation of second order in matlab

I have a problem solving a system of differential equations of second order in matlab: $$ \left\{ \begin{array}{l l}\frac{d^2y}{dt^2}= \frac{-y}{(x^2+y^2)^{3/2}}\\ \frac{d^2x}{dt^2}= ...
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1answer
719 views

Determining the value of ECDF at a point using Matlab

I have a data $X=[x_1,\dots,x_n].$ In Matlab, I know by using [f,x]=ecdf(X) plot(x,f) we will have the empirical distribution function based on $X$. Now, if ...
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1answer
73 views

Understanding the transformation of values when plotting logscale in Matlab.

I'm playing with some transistor test data and having trouble understanding what is probably a very basic principle. Below are my two graphs, plotted linearly and then with a logarithmic scale on the ...
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1answer
99 views

MATLAB Feedback

I am trying to use the feedback function in matlab and for the most part I understand it. But I came across this syntax: [x1 x2] = feedback(sys1, sys2, 1, 1, -1); ...
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1answer
171 views

How to convert rational numbers to irrational numbers in disp in Matlab

How can I convert rational numbers to irrational numbers in $\operatorname{disp}$ in Matlab? I wrote a method in Matlab to estimate the value using the Newton-Raphson Method but when I use ...
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1answer
98 views

Where is the fixed point? — Matlab is cluless too

Consider the differential equation $$\dot{k}(t)=f(k)-(r+t_1)k-f(1-k)+(r+t_2)(1-k)$$ where $k,t_1,t_1\in[0,1]$, $r\in\mathbb{R}$ and $f:[0,1]\to\mathbb{R}_+$. I'd like to solve for the fixed point ...
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2answers
105 views

MATLAB Eigenvalues

So I am trying to get matlab to output the correct eigenvalue/eigenvector of a matrix. The matrix is: \begin{array}{ccc} 0 & 1 \\ -3 & -4 \end{array} The eigenvalues are: $\lambda_1 = -1, ...
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0answers
313 views

Matlab project - Jacobi method for tridiagonal matrices…

I have to do a project in Matlab to my University and I don't quite understand what I should do. I was given script that solves systems of equations with Jacobi's method with given tolerance and ...
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1answer
39 views

Large error after factoring h from fourth-order Runge–Kutta method

Consider $$\frac{dy}{dx} = 2x-y, \qquad y(0)=1$$ That has an exact solution $y(t) = 2t+3 e^{-t}-2$. But I want a numerical solution. So I decided to use forth-order Runge–Kutta method ...
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1answer
87 views

Matlab calculate output

I'm trying to write a matlab function that takes in a transfer function and the input so it can calculate the output. So far, based on this information under I have the following piece of matlab ...
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1answer
88 views

Roots of an equation using Maple

I am using Maple to find the roots of a non-linear equation in one variable. When I solve the equation, I get only 2 negative roots whereas if I plot the graph of the function, it also shows that the ...
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1answer
191 views

Incorrect angle detected between two planes

I want to calculate the angle between 2 planes, Reference plane and Plane1. When I feed the X,Y,Z co-ordinates of pointCloud to the function plane_fit.m (by Kevin Mattheus Moerman), I get the output ...
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1answer
276 views

Beta-binomial random number generator

Could someone help me find a random number generator from a Beta-Binomial distribution in MATLAB, R or SAS? Thank you!
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1answer
43 views

Building an nth order ODE in Maple (or Matlab)

The question is simple: given a system of ODEs, how can one construct the equivalent nth order ODE in Maple? In my case I have $$ \begin{cases} y''(t)+x'(t)+x(t)=f(t)\\ y''(t)+z''(t)+z'(t)+z(t)=0\\ ...
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1answer
639 views

Inverse Power Iteration converges to largest eigenvalue instead of smallest?

I am trying to write a Matlab function that takes a matrix and an iteration count and performs inverse power iteration to output the smallest eigenvalue. The problem is, as k increases, the function ...
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1answer
976 views

create a Gaussian distribution with a customize covariance in Matlab

the Matlab function 'randn' randomize a Gaussian distribution with $\mu= \begin {pmatrix} 0\\0\end{pmatrix}$ and $cov= \begin {pmatrix} 1&0\\0&1\end{pmatrix}$ Ineed to randomize a Gaussian ...
2
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1answer
88 views

Higher order numerical PDE schemes near boundaries, implementation in MATLAB

Followup to my previous question. The first order scheme proved unstable for my pde: $$f_t + A y f_x - B x f_y =0$$ So I'm looking to implement a higher order scheme (using these tables). I was ...
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1answer
34 views

Fitting a polynomial model to the data

I want to fit a line to the following data. But the line I have obtained is far from the data. What is wrong in the following least square problem? ...
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0answers
875 views

Low rank approximation using CVX toolbox in Matlab

I try to use CVX toolbox to do "low rank approximation" work. The code is as follows: ...
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1answer
713 views

Simulink model from a nonlinear State Space

I have the nonlinear state space already constructed in MuPAD as shown: u is the input and y is the output. What is the best way for me to take this to Simulink?
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1answer
160 views

How to draw or plot illustrative figures?

stackexchange users I would like to plot or draw some illustrative figures for my research paper. I've tried GeoGebra already. But couldn't draw them as I wanted. So my question is How can I draw ...
2
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0answers
1k views

How to find the Total Harmonic Distortion of a Periodic Signal through MATLAB?

How to find the Total Harmonic Distortion of a Periodic Signal through MATLAB? I just need help in confirming if my way of approach to finding the THD seems valid, I'm new to MATLAB so I'm not quite ...
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1answer
165 views

MATLAB, 1st order 2d hyperbolic equation, problem with convergence.

Follow up to my previous question: MATLAB: solving 1st order hyperbolic equation in 2 spacial dimensions The equation I'm solving has the form: $$f_t + A y f_x - B x f_y =0$$ I wrote the following ...
2
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1answer
44 views

Weed out numerical artifacts from matrix inversion

I am working with the inverses to a set of large sparse matrices (in Matlab). A key indicator for my application is the number of non-zero entries in each row, and I recently discovered that I was ...
2
votes
1answer
222 views

MuPAD - complicated solve() solutions

I am trying to solve an equation for one variable as shown in the picture: Judging from the output of the second command, I should be able to get an expression for $\ddot{\theta}$. I tried ...
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3answers
49 views

How do I define this matrix in matlab?

$$A = \begin{pmatrix} 2 &-1 & 0 & \dots & 0 \\ -1 & 2 & -1 & \ddots & \vdots \\ 0 & \ddots & \ddots & \ddots & 0 \\ \vdots & \ddots & -1 & 2 ...
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1answer
314 views

MuPAD - rearrange an equation

I have a huge expression, say $f(x_1,x_2,x_3) = 0,$ and I want MuPAD to try to express $x_1 $ in terms of $x_2$ and $x_3$ Is this possible?
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1answer
90 views

MuPAD equation solving

I have x(t) defined as: x(t) = Symbol::subScript(x,0) + Rb*`φ`(t) I want to write the derivative of ...
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1answer
103 views

How can I integrate over an infinite interval in Matlab? [closed]

Would you please help me integrating the following function over an infinite interval in Matlab. Many thanks $$ \int_{-\infty}^{\infty}P(\lambda)P(0.1-\lambda) e^{-j2\pi \lambda} $$ In which ...
2
votes
1answer
56 views

Is there a function in MATLAB that will estimate the initial condition from a set of data?

I was given a state-space model of a system and a list of outputs for t=0 to t=5, sampled every 0.1 seconds and asked to approximate the initial condition. Is there a function in MATLAB that will take ...
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1answer
302 views

MATLAB: solving 1st order hyperbolic equation in 2 spacial dimensions

According to wikipedia, the equation $$\psi_t + \mathbf{u} \cdot \nabla \psi =0$$ is hyperbolic. However, when I want to solve it in MATLAB using the pde toolbox (link), the general formula for a ...
2
votes
0answers
72 views

Simulation Velocity of a harmonic oscillator system

I am write a simulation for get true Velocity of a harmonic oscillator system as Where P=[p1 p2;p2 p3] can find using Rung-Kutta Integration method with P(0)=[1 0; 0 1] This is code to find p Now, ...
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0answers
38 views

Optimizing rank computation for very large sparse matrices

I have a sparse matrix such as ...
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1answer
1k views

How do I plot normal distribution

If I know the range (1-24) and know the area (X), how can I plot a normal distribution so that the curve has area X?
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1answer
24 views

plotting an fft function

need to plot the folowing: $$X(j\omega)=\cal F\{{2\over\pi\lambda}\}*\cal F\{sinc(2w_m\lambda)\}-\cal F\{{4\over\pi\lambda}\}*\cal F\{sinc(w_m\lambda)\}$$ as a plot of $|X(j\omega)|$ for ...
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2answers
59 views

Would taking a course in Linear Algebra help with working with Matlab?

I'll soon be using Matlab in an engineering course I'll be taking next semester. So given how Matlab stands for Matrix Laboratory and Linear Algebra has a lot of matrices involved, does such a Linear ...
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1answer
232 views

fourier transform in matlab

getting an error while trying to do fourier transform. my code: ...
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1answer
222 views

Plotting multiple curves using ODE45

I am a beginner to using MATLAB, and I need a lot of help to understand what to do here. I would like to plot multiple curves using different initial conditions to my system of ODEs. Here is my ...