# Tagged Questions

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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### Cyclic Redundancy Check of an input sequence using MATLAB

I understand how to mathematically calculate the cyclic redundancy check CRC of bits, for example if the CRC is of length 16 $$CRC(D) = (M(D) + I (D)) D^{16} \,\,\, mod \,\,\,\ G(D)$$ where $M(D)$ ...
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### What is transpose multiplier and forward multiplier?

For linear system X = A*s, we define the forward and transpose multiplies Af and At as follows: Af = @(s) A*s; At = @(s) A'*s; I want to know what is forward ...
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### Please help: My MATLAB code for solving a 2D Schrödinger equation keep giving me weird output.

I've been trying to solve the following Schrödinger equation numerically, -(\frac{\partial^2}{\partial y^2} + \frac{\partial^2}{\partial z^2})\Psi + \frac{\sinh^2(y) + ...
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### Matlab, Extracting Particular Values from an Excel File

If I have a table of values in Matlab ( here I have a 40k rows, and about a dozen columns), how can I read only particular values from each row? My goal is to extract some of the values from each row, ...
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### Numerically solving equations with expectations

I have a equation $\mathbb{E}_\theta f(x,\theta)=a$, where $\theta$ is a vector real random variable with a known distribution, $a$ is a real constant, $x$ is a real (can be vector valued) variable. ...
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### Inverse Chebyshev Recurrence

The Chebyshev polynomials (of the first kind) are a sequence of polynomials defined recursively by $$\begin{cases} T_{0}(x) = 1 \\ T_{1}(x) = x \\ T_{n}(x) = 2xT_{n-1}(x) - T_{n-2}(x) \end{cases}$$ ...
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### Solve first order BVP on MATLAB

I try to solve this equation on MATLAB $$y^\prime(x)=x+y^2(x)\quad\forall x\in(0,0.9),\quad y(0)=1, y(0.9)=32.725$$ I write two function on matlab, on myODE.m file, ...
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### Does rotation of a rectangle keep it rectangular?

If I rotate a rectangle by 45°, does it stay rectangular or become something else? I mean do 90° angles stay 90°? I am asking this question because I have some results where the rotated rectangle ...
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### QR and Cholesky decomposition

A while ago I asked for help to develop a polynomial regression model using least squares, where the system was solved by cholesky decomposition, you can check it here Cholesky Polynomial Regression ...
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### Correlation between ordinal variables

I want to know the correlations between 3 groups of variables which are oridinal (rating of 1 to 10). I have followed the formula on wiki and computed the Kendall tau-b correlation coefficients ...
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### How to plot $\int\frac{\mathrm{d}y}{W(-e^{-y^2/2-1})+1}=x$ in Matlab?

I would like to plot in Matlab the following implicit equation: $$\int\frac{\mathrm{d}y}{W(-e^{-y^2/2-1})+1}=x,$$ where $W(\cdot)$ is the Lambert $W$ function. I am trying to plot it symbolically ...
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### Inflow and outflow of Traffic graphs

For my bachelor thesis I am making a model for calculating a distribution of traffic in a network/graph given the delay on the links of the graph. I have written a Matlab program, and it seems to ...
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### Solving 2nd order ODE with 2 independent parameters(over finite intervals), with bounds on solution

I have a 2nd order ODE of the form: $\ddot {x} + 2c \dot {x} + 39Ex = 0$ $Initial$ conditions being: x(0) = 0 and $\dot {x}(0)$=0.1 Where c is in the interval [1,5] and E is in the interval ...
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### Error estimation - spline interpolation

I got a question regarding error estimation and spline interpolation. I got a parabola shaped graph that I've used spline interpolation on to get more accurate data. I've used a much smaller step on ...
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### How to calculate Gradient of a vectorized equation.

I am solving a huge optimization problem in Matlab. I am now required to obtain gradient of objective function,and nonlinear constraint along their hessien matrix. ...
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### Cholesky algorithm

Good afternoon everyone, I'm in need of a factoring algorithm cholesky and algorithms to solve upper and lower triangular systems, but I'm not finding any work in that octave. Recalling that need the ...
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### Least Squares method and Octave/Matlab [closed]

I'll try to be as clear as possible so that you understand what I'm trying to do and can help me I have twelve pairs of data $(x_1,y_1),....,(x_{12},y_{12})$ and from this data we established a model ...
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### randomly rough surface by ifft : real output from ifft

I'm trying to generate a randomly rough isotropic surface with predefined roughness amplitudes (standard deviation of heights). Suppose I have the absolute values of fourier components of the surface ...
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### Sorting signals to achieve highest possible similarty

I am currently trying to develop an algorithm in Matlab that sorts signals, which I have as columns of a matrix, to achieve the highest possible similarity of the signal with its neighbors. My first ...
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### MATLAB: minimize function using x value from previous iteration

I'm trying to develop an algorithm for a proximal point method defined as: $$\underset{x \in \rm I\!R^n}{\arg\min} f(x) + \lambda g(x)$$ where f(x) is a convex and coercive function and also ...
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### Implementing Ornstein–Uhlenbeck in Matlab

I am reading this article on Wikipedia, where three sample paths of different OU-processes are plotted. I would like to do the same to learn how this works, but I face troubles implementing it in ...
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### please how to rotate a matrix $5\times4$ by 45° around the origin $(0,0)$? using matlab

Suppose I have a matrix $M$ of $5\times4$ dimension (this is represent an image) : M = [3 4 8 9; 1 6 7 3; 9 8 3 1; 1 2 2 0; 7 2 3 5]; ...
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### Covariance from Gaussian Mixture Model versus direct calculation

I have a random variable $T$ which can be expressed as follows: $T=c_1P\cdot f+c_2Q$, here $\cdot$ denotes point-wise multiplication. $c_1,c_2$ are scalars and treated as constants. Distribution of ...
I'm using Gauss-Legendre Quadrature to solve the following integral: $\int_0^{1}x^xdx$ After I've compared the result with the MatLab vpa(int(...)) of the same integral I've noticed that the ...
I have some sets of experimental data for some functions $f_i$ from $I=[0,1]$ onto itself, which should satisfy the following physical constraints: $f_i(0)=1$ \$f_i(x) \in I= [0,1] \; \forall x \in I ...