I like to use MySQL to do quantitative analysis and statistics. I would like to make a MySQL user-defined function of the form: sample_gaussian(mean, stdev) that returns a single randomized value sampled from a gaussian distribution having mean and standard deviation of the user-entered arguments. MySQL already has a function rand() tha...
I would use a multi dimensional gaussian modell for regression. Rasmussen has a book with an algoritm, but it is only for one dimension output. Any idea to modify it? ...
Assume I have a set of weighted samples, where each samples has a corresponding weight between 0 and 1. I'd like to estimate the parameters of a gaussian mixture distribution that is biased towards the samples with higher weight. In the usual non-weighted case gaussian mixture estimation is done via the EM algorithm. Does anyone know an ...
Does the 'gaussian' filter in MATLAB convolve the image with the Gaussian kernel? Also, how do you choose the parameters hsize (size of filter) and sigma? What do you base it on? ...
This picture from wikipedia has a nice example of the sort of functions I'd ideally like to generate http://en.wikipedia.org/wiki/File:Normal_Distribution_PDF.svg Right now I'm using the Irwin-Hall Distribution, which is more or less a Polynomial approximation of the Gaussian distribution...basically, you use uniform random number gene...
I'm using R. I have 25 variables over 15 time points, with 3 or more replicates per variable per time point. I've melted this into a data.frame, which I can plot happily using (amongst other things) ggplot's facet_wrap() command. My melted data frame is called lis; here's its head and tail, so you get an idea of the data: > head(lis) ...
I have been using Math.Round(myNumber, MidpointRounding.ToEven) in c# to do my server-side rounding, however, the user needs to know 'live' what the result of the server-side operation will be which means (avoiding an ajax request) creating a javascript method to replicate the MidpointRounding.ToEven method used by c#. MidpointRounding....
When applying a Gaussian blur to an image, typically the sigma is a parameter (examples include Matlab and ImageJ). How does one know what sigma should be? Is there a mathematical way to figure out an optimal sigma? In my case, i have some objects in images that are bright compared to the background, and I need to find them computation...
Hello, I am attempting to perform a zero-crossing edge detection on an image in OpenCV. I blur and use the cvLaplace() then scale it from (0, max). My question is: How can I access the pixel values in that image in such a way as to correctly identify negative values? Using the function provided by OpenCV (cvPtr2D) returns unsigned chars...
I do not understand what a convolution kernel is and how I would apply a convolution matrix to pixels in an image (I am talking about doing a Gaussian Blur operation on an image). Also could I get an explanation on how to create a kernel for a Gaussian Blur operation? I am reading this article (http://en.wikipedia.org/wiki/Gaussian_bl...
Hi, im trying to implement a gaussian blur with the use of FFT and could find here the following recipe. This means that you can take the Fourier transform of the image and the filter, multiply the (complex) results, and then take the inverse Fourier transform. I've got a kernel K, a 7x7 Matrix and a Image I, a 512x512 Matr...
I would like to know the cheapest, dirtiest approximation of the Gaussian cdf. Would it be a Taylor series or this method: http://www.cs.princeton.edu/introcs/21function/ErrorFunction.java.html ...
hi, I want to generate some random integers in Java, but this according to some distribution laws. More specific: I want to generate some random integers for gaussian distribution. I found out only generators which return double results for the gaussian distribution. Why is that? I want to generate some random integers between some li...
Can you please tell me how can I model a Gaussian Basis Function in a 2 Dimensional Space in order to obtain a scalar output? I know how to apply this with a scalar input, but I don't understand how should I apply it to a 2 dimensional vector input. I've seen many variations of this that I am confused. ...