Questions tagged [gaussian]

For issues related to any of the uses of the Gaussian function. Don't forget to add additional tags to clarify the context.

The graph of a Gaussian is a characteristic symmetric "bell curve" shape that quickly falls off towards plus/minus infinity. The 1-D Gaussian is defined as (taken from wikipedia):

gaussian function from wikipedia

The parameter a is the height of the curve's peak, b is the position of the centre of the peak, and c controls the width of the "bell".

In multiple dimensions, the Gaussian is defined as the product of 1D curves along each dimension.

Gaussian functions are widely used in statistics where they describe the normal distributions, in signal processing where they serve to define Gaussian filters, in image processing where two-dimensional Gaussians are used for Gaussian blurs, in mathematics and physics where they are used to solve heat equations and diffusion equations, to formulate the propagation of optical beams (Gaussian beams), to from a basis set of wavefunctions, to define the Weierstrass transform, and many more.

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java function random number between -0.5 and 0.5 with gausian distobution

I'm currently trying to make a random number between -0.5 and 0.5 in this way: public static double RandomNumberGenerator(long seed) { Random r = new Random(seed); return r.nextDouble() >= 0.5? 0.5 : -0.5; //PRINTING AND USAGE, SHOULD…
smatthewenglish
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Bayes Classification with Multivariate Parzen Window using Spherical Kernel

I'm having a problem implementing a Bayes Classifier with the Parzen window algorithm using a spherical (or isotropic) kernel. I am running the algorithm with test data containing 2 dimensions and 3 different classes (For each class, I have 10 test…
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Apply cwt in Matlab

I'm trying to implement an algorithm which has been described in a paper. It deals with accelerometer data which has to be filtered and differentiated. My input is a vector (1 column, multiple rows). As described here The vector has to…
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Generating random noise in matlab

When I add Gaussian noise to an array shouldnt the histogram be Gaussian? Although the noise is random, the distribution should be gaussian right? That is not what I get. A=zeros(10); A=imnoise(A,'gaussian'); imhist(A)
dither
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conditional probability density from GMM

I have fitted a Gaussian Mixture Model to the multiple joint probability density functions. How can I obtain the conditional probability density function (i.e.,p(x|y)) from this mixture model (NXN matrix) in Matlab?
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Optimizing an optimization

I have a discrete data set with multiple peaks. I am trying to generate an automatic method for fitting a Gaussian curve to an unknown number of data points. The ultimate goal is to provide a measure of uncertainty on the location (x-axis) of the…
Jesse
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Data fit to Multivariate Gaussian Curve

I have an image of a proton beam hitting a scintillator sheet. This image was filtered to a grey-scale 8-bit bmp file. I can use python/matlab to basically get a large list of data points, where each point consist of an (x,y) position and a (z)…
Mike
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Android gaussian blur on part of an image

I am trying to implement a feature in the app that blurs some part of an image based on users selection/touch. I have suceessfully applied the Android's "RenderScript" method to blur full image however, I can't find an example of blurring only some…
Sahil
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Variance using Gaussian distribution Python

I have a code which calculates the square of a number using Gaussian distribution in python. Now my task is to calculate the variance for the same. But when I try, i keep getting error. The code is as follows: import random def generate_data(size): …
Sandy.Arv
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square of a number using gaussian distribution

Is there a way to calculate the square of a number (closest approximation), say 4, using Gaussian distribution where mu is the number and sigma is 0.16. and for 1000 random points? I searched the internet a lot, but couldn't find a solution to this.…
Sandy.Arv
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UIImageEffects: white image when Gaussian radius above 280, vImageBoxConvolve_ARGB8888 issue?

I'm using the Gaussian blur algorithm found in Apple's UIImageEffects example: CGFloat inputRadius = blurRadius * inputImageScale; if (inputRadius - 2. < __FLT_EPSILON__) inputRadius = 2.; uint32_t radius = floor((inputRadius * 3. * sqrt(2 *…
Archagon
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Generating dataset with mean, std dev, and number of samples

I am trying to generate a 2D data set with the following parameters: x= N(-5,1) y= N(0,1) n= 1000 Where N(mean, std dev) and n = number of samples. I tried: x = normrnd(-5, 1, [100,10]) y = normrnd(0,1,[100,10]) to generate a 100 x 10 array with…
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MATLAB fitgmdist: Verbose Mode?

I am using MATLAB's fitgmdist ("fit a guassian mixture to data", from the Statistics and Machine Learning Toolbox) with some success. Is there a way to make it run in a verbose mode, e.g., tell me what iteration it is on, or show convergence stats…
Novak
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Why does Armadillo fail to learn a Gaussian Mixture Model and complain about 'no existing means' despite random_subset seeding?

QUESTION SUMMARY: I have a [5 x 72580] matrix. I am trying to fit a Gaussian Mixture Model (GMM) to this data using the gmm_diag.learn() method with random_subset as the initial seeding mode. Why does Armadillo display "gmm_diag::learn(): no…
sid
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R loop producing "replacement has length zero"

I have this code snippet in R: for(i in 1:n-1){ for(j in 2:n){ mult = (matrx[j,i]/matrx[i,i]) vector = matrx[j,] - (matrx[j-1,] * mult) print(vector) # matrx[j,] = vector } } The code prints the vector variable correctly,…
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