# Tagged Questions

MATLAB is a high-level language and interactive programming environment developed by MathWorks. It is the foundation for a number of other tools related to statistical analysis, including Statistics Toolbox, Optimization Toolbox, Curve Fitting Toolbox and Neural Network Toolbox.

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### error in logistic regression

I am new to this forum and beginner in Matlab implementation. Kindly, if some one can help me out why my accuracy isn't increasing in training. My problem is as follow: Implement an optical character ...
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### Issue in graph construction

I have a symbolic representation of time series obtained from SAX toolbox. I was wondering if it is possible to construct a graph where each node represents a unique symbol and the edges represent the ...
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### $\chi^2$ test in MATLAB — vector different length [migrated]

I have 3 data vectors representing the gender (0=male, 1=female) of 3 groups A, B, C. for example ...
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### Test data generation for neural network handwriting recognition

Can someone share some Octave/Matlab code or algorithm to pre-process a photo taken from mobile camera of a handwritten digit. After pre-processing, the data should have similar characteristics to ...
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### Plot PDF and CDF for normal distribution in matlab [migrated]

I couldn't find functions in matlab's API (including in the statistical toolbox) that implement functions which get as input: $\mu$ and $\sigma$ for normal distribution and plot the PDF and CDF. If ...
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### Characterizing a time-series using autocorrelation lag values

I am seeking to characterize time-series data (specifically parameters derived from sensor data) for 18 patients collected over 20 days using autocorrelation (see plot below of autocorrelation ...
296 views

### How to test equality of variances with circular data

I am interested in comparing the amount of variability within 8 different samples (each from a different population). I am aware that this can be done by several methods with ratio data: F-test ...
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### 2SLS with two instruments for one endogenous variable in MATLAB

I have one endogenous variable and two instruments for it, and I want to calculate my beta with the direct (one step) matrix formula $\beta_2sls = X' Z(Z'X)^{-1}Z'X^{-1}X'Z(Z'Z)^{-1}Z'Y$ But if I ...
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### Problem in finding fractal dimension (correlation dimension)

I am trying to implement Takens correlation dimension formula given in Eq (8) in Paper1: Estimation of the dimension of noisy attractor (Estimation of the dimension of a noisy attractor. Schouten JC, ...
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### How many days are required for neural network prediction of dax future?

I am predicting the daily change of the dax future. Input data I am using: Dax, vdax, euro bund spy500 close prices as returns 8 series from investor series having values between 5 and -5 This is ...
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### Pattern classificaton using neural network learning

Paper1 (freely available) and Paper2 (Springer) talk about application of fuzzy cognitive map (FCM) for pattern classification. I am having a tough time to understand how the equation of FCM is ...
152 views

### What is the difference between different kind of cross validation methods?

Now I am using MATLAB, and found one of its function named crossvalind, which provides lots of methods for cross validation, including some that I wasn't able to ...
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### k-means implementation with custom distance matrix in input

Can anyone point me out a k-means implementation (it would be better if in matlab) that can take the distance matrix in input? The standard matlab implementation needs the observation matrix in input ...
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### Hopfield neural net cannot store more than 2 association patterns

I'm just trying to implement a simple discrete Hopfield net using Matlab but there is a problem with my result. As I present two patterns to be stored in my net everything works great and I can ...
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### Issues with using glmnet package for matlab

I am trying to use glmnet-matlab pacakge for training my elastic net model on some huge data. My features are of size 13200 and I have around 6000 samples of these. I directly tried to use lassoglm in ...
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### Matlab textscan problem [migrated]

I have a .txt file like this: ord,cat,1 ord,cat,1 ord,cat,3 ord,cat,1 ord,cat,4 I know the number of entry for each row (comma separated) but not the number of rows. I need to import the number ...
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### How to use Gaussian Mixture Models for clustering new data?

I applied Gaussian Mixture Model on my data and train the model in MATLAB. How I can test my model or use it to cluster new data? Thanks for any answer or comment.
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### Libsvm parameters (c, g, p) search [migrated]

Is there a way to find the libsvm parameters (c, g, p) for REGRESSION in MATLAB? It's ok to find them with gridgregression.py but what if we want to use them in Matlab? It is a bit timespend to ...
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### PCA on returns or levels?

I am doing a PCA on a few economic indices (which I standardized) (24 timeseries). When doing the PCA on the values/level of the index, I get rather similar loadings on each index, which I think is ...
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### Generlized Cross Validation in Matlab

I want to use Generalized Cross Validation to compute the optimal ridge parameter for a ridge regression. The formula due to Golub et al (1979) is GCV(k)=(1/n Sum_i=1^n e_i(k)^2)/(1/n ...
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### What data from MATLAB's svmstruct are needed for classification in a different language?

As the title already states Iam wondering what data exactly are needed from the MATLAB svmstruct to be able to classify a new instance outside of MATLAB, e.g. in ...
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### Calculating precision-recall curve from error matrix in MATLAB

How is a precision-recall curve calculated from an error matrix and vector of labels? The error matrix is of size NxN, and contains distances between the features associated with the respective row ...
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### Numerical example for MLE for linear regression model

I need to calculate the log-likelihood for a linear regression model in MATLAB. Although the theoretical result is well know and given in several sources, I want to find a numerical example so that ...
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### GPML gives too large length scale when optimising hyperparameters

I recently started trying to apply Gaussian process regression to a problem, using the MATLAB GPML toolbox. The problem has five (or more) input variables, but for now I'm just looking at one of them. ...
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### A MATLAB package to calculate Entropy of a discrete non-stationary (hydrologic) time series

I am looking to survey the community to find out any prefered packages researchers, practitioners, or interested modelers are using to calculate entropy (cross-entropy, conditional entropy, etc...) ...
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### Outlier detection and smoothing for multi dimensional time series

From kinect depth images, I have collected the following time series that represent the features = 3D joint positions, quarternion angles, difference between hip joint and centroid of the right arm ...
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### Differences between clustering and segmentation

I have read about piecewise aggregate approximation (PAA) mining time series data, sliding window, top down and bottom up approaches for time series segmentation but these are applicable to single ...
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### Performing ridge regression with multiple outputs in MATLAB

Is there any way to do ridge regression in MATLAB with multiple outputs. I mean the ridge function by default just supports one output?
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### Gap statistics MATLAB implementation

Does any know the reference/link where i can find the MATLAB implementation of gap statistics for clustering as mentioned in this paper?
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### Neighborhood analysis in Matlab using a dot plot

I have points in a 2D graph (coordinates: X,Y property: Z). I would like to find for every point the closest, for example, 5 points and save their properties. What would be the easiest approach? ...
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### Libsvm one-class svm: how to consider all data to be in-class

I am using Libsvm for Matlab. I would like to construct the model for a full circumscription of all training data (in the higher SVM-space). For this I assume all my training data is correct and has ...
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### What languages are commonly used in medical statistics?

A doctor friend has asked if I would teach them some basic programming, because they think it will be useful when they start to do research in the future. To give some background - they don't know ...
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### Error bars for unknown distributions

I recently made a graph where I show the error bars for a certain number of "experiment". In another way, in my algorithm I'm minimizing the objective function so I would expect that increasing the ...
218 views

### Bootstrapping residuals: Am I doing it right?

First of all: From what I understood, bootstrapping residuals works as follows: Fit model to data Calculate the residuals Resample the residuals and add them to 1. Fit model to new dataset from 3. ...
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### SVM: plot multi dimensional data when implementing multiclass one-vs-all or one -vs one?

I have split the multi class svm to several binary classifications and obtained the individual predictions. My predicted labels are saved in a matrix 'predicted_vals' with each row containing ...