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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The covariance matrix is not positive definite in a classification task in Matlab

I am trying to perform a simple classification task in Matlab. I have an NxM matrix F with rows representing the samples and column representing the features (that is my training set). This is fed to ...
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Matlab nn tool data interpretaion regression equation [on hold]

How to get predicted data and regression equations in nn tool using matlab software i need the set of commands to get the same
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How to extrapolate this simple trend line into the future for the purpose of forecasting in Matlab?

We have the following data points in variable data pertaining to a problem that we are solving: ...
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Programs to read an arbitrary image and convert it to the format of MNIST dataset [on hold]

I want to make a program that turns a given image into the format of the MNIST dataset, as a kind of exercise to understand the various preprocessing steps involved. But since the description of how ...
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How to fit a forecasting model on this irregular time series in Matlab to obtain predictions? [on hold]

We have some data values from the past (1214415 to be exact over 1 minute intervals). We are only interested in the 'peaks', that is, how the trend pertaining to the maximum is increasing with time. ...
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Should outliers be removed from Principal Components Analysis?

I have calculated Hotelling's T2 statistic for detection of outliers in PCA analysis in Matlab. However, I am unsure as to whether or not it is a robust approach to remove these outliers? The output ...
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Estimation and forecasting ARMA: differences between Matlab and Stata

I have to forecast values from an AR(1) model. My sample is composed of 192 observations. I estimate my model with the 182 first observations and forecast the 10 last observations. I have done this ...
19 views

Nesterov accelerated gradient descent in neural networks

I have a simple gradient descent algorithm implemented in MATLAB which uses a simple momentum term to help get out of local minima. ...
21 views

SURF algorithm failing?

I am currently working on misalignment correction and after some research found a nice matlab toolbox for this purpose capable of doing Lucas-Kanade, ECC among others. I had success when using a ...
8 views

0-centering a kernel matrix: which formula is the correct one?

I'm trying to implement the algorithm in this paper. As you can see at page 4, it is explained how to 0-centering a pxp symmetric Kernel matrix ...
30 views

A (simple) example where LSTM works but a regular Neural Network (NN) fails?

In the spirit of the answer from maple on this thread: Using RNN (LSTM) for predicting the timeseries vectors (Theano) I created some simple sine wave data to fit with a LSTM. It worked well! ...
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Is there a way to test if the co-variate distributions of two matrices (two sets) is same?

Is there a way to test if the co-variate distributions of two matrices (two sets, for example, the training set and the test set)? For example, the training set Xtr is a 200-by-10 matrix, and the ...
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Nonlinear transformation using the beta distribution

I'm trying to estimate the following equation (abstracted from this paper) in Matlab: $y_i=a+b\frac{(x_i-min(x))^{(c-1)}(max(x)-x_i)^{d-1}}{B(c,d)(max(x)-min(x))^{c+d-1}}+\epsilon_i$ where $B(c,d)$ ...
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how to perform on a validation set?

Hello suppose i am creating a feed forward neural net and also training it with backpropagation. I am having three different sets training testing and validation.How do I apply training on the ...
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Why does executing a PCA on my unbalanced dataset change the prediction distribution of my test so much?

I'm using prtools to try and solve a machine learning problem and trying to use a PCA to help me with this. Now I have a dataset with 13 features (columns), 10000 ...
36 views

Using lasso regression in Matlab with constraints on lambda values

I have successfully ran a lasso regression on Matlab, however, some of the lambda values result in a non-steady state solutions for my linear problem. I would like to basically force the regression to ...
15 views

Curve fitting of Abs(A+M0*(1-2*B*exp(-t/T1)))

I apologize for the less-than-descriptive naming of this post, but I could not think of what this kind of function was called. I am trying to fit MRI T1 relaxation time to a curve: \$M(t)={\rm abs}(A+...
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Rolling window for the lasso regression in MatLab

My objective is: rolling window for lasso regression. I explain what I tried to do: I used "lasso function" -> [B, FitInfo] = lasso(X,y,'CV',k), where the output "B" is a matrix pxL, where p is the ...
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Matlab : How to apply neural network for binary input features

I have inputs that were real valued. I then normalized them to a range [0,1] and binarized using the mean of each feature component (column) using the solution given in the earlier Question asked ...
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How to combine two models (neural network and KNN) in Matlab?

I am conducting research on credit risk prediction using neural networks and K-Nearest Neighbour models (K=10) in Matlab. The dataset has 490 samples with 19 features, from which I want to predict 1 ...
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How to calculate normalized euclidean distance on two vectors?

Let's say I have the following two vectors: x = [(10-1).*rand(7,1) + 1; randi(10,1,1)]; y = [(10-1).*rand(7,1) + 1; randi(10,1,1)]; The first seven elements are ...
27 views

Proper way to scale feature data

I am using Iris dataset and trying to scale the feature to the range [0,1]. After normalization, I want to binarize the feature. The iris database contains n = 150 ...
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How to model my data with linear mixed models for contrasts analysis

I have a dataset containing one dependent variable which is the concentration of antibiotic needed to kill a bacteria, which was measured for several different antibiotics for three different ...
22 views

Results of Softmax regression on MNIST dataset

I'm currently following this lesson: http://ufldl.stanford.edu/tutorial/supervised/SoftmaxRegression/ , and after I coded their equation I got: ...
38 views

Obtaining distribution from histogram

I have an array of values, with those values I plotted the histogram, calculated mean and variance. I want to know the corresponding distribution from the histogram obtained. How is it possible? Could ...
21 views

2d points distribution with shifted centroid

How can I have a distribution with centroid being away from center? i.e. points distribution starts out dense, and then goes on to become sparse, but with NO sudden transition? Pl find the image ...
37 views

Implementation of PCA using SVD without creating covariance matrix [duplicate]

So I'm currently taking a Machine Learning course and have correctly submitted my implementation of PCA. I used SVD. Here it is Octave. ...
59 views

Logistic Regression or Linear Regression

Say I have the following hypothetical scenario: I have a material that I can freely configure, starting with 10 different strength properties. ...
23 views

variance of a mixture in terms of the mean and variance of each component

I am following the MATLAB example to fit a mixture of two normal distribution that you can find here At some point it is defined the inital guess for the standard deviation as: ...
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How to compute percent of variance explained in X and Y for each component of a PLSR?

I am not a mathematician and my question is probably trivial but I did not manage to find an answer on the web. I need to compute the percent of variance explained (eigenvalues?) in X and Y for each ...
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How to use logic gates with time-series values simulink?

In Simulink, based on the comparison between a constant and a time-varying series, I want to generate another time varying series. But the problem is: when I try to directly compare the two signals ...
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Is Logistic Regression Appropriate for this Question?

I am attempting to predict the ranking of NBA teams next season based on the number of games they won this season. To do this, I thought I could use a logistic regression with historical data. As ...
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I have been instructed by my supervisor to run K-means in Matlab on my data which is comprised of sensory data observations that pertain to 7 outcomes, which I have labeled using numbers from 0 to 7. ...
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Matlab : Correct way of determining mean in post-processing of features

I need to post process the feature vectors of N = 1000 images, each of dimension m = 100 converting the real valued features to ...
90 views

TOO low estimated SVM probability for most of the negative test examples?

I am using LIBSVM (as well as the fitcsvm and fitSVMPosterior of ...
33 views

How am I going to understand this bootstrapping?

I already feel like I'm spamming this site! However, after several days of scratching my head and thinking things over, I cannot really answer this myself. I want to get a confidence interval of the ...
39 views

Cross validation function from which programming language is more appropriate? [closed]

I'd like to use resample to achieve stable results of an unsupervised algorithm that finds clusters in data. I'll use k-fold cross validation repeated many times but I'm in doubt if I should use R or ...
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Why are there three parameters that can change during batch normalization according to MatConvNet implementation?

I was going through the MNIST example that comes with MatConvNet were they attempt to demonstrate how to use the API of their Batch Normalization. However if you take a look at the training file there ...
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Is it possible for the forward pass computed by a wrapper to not agree with a hard coded using MatConvNet?

I was implementing a super duper simple network and I wasn't able to have the forward pass match for both the wrapper and the hardcoded version of the network: ...
35 views

How can I compute statistical significance with cross-validation? [duplicate]

I've done nested cross-validation with 10 outer runs and 10 inner runs to evaluate different classifiers. In the end I average the accuracies of the 10 outer cross-validation runs to get a final ...
36 views

statistical difference between two linear regression slopes in matlab

I have the following data, which I'm analysing in matlab: ...
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Merge column vectors from the loop in to a single matrix *.mat in matlab [Solved] [closed]

I have an iteration of my algorithm and it gives me a column vector as a result (1899x1 double). I want to form a new matrix composed of these column vectors together sequentially (for example, the ...
24 views

How to visualize regression features?

In classification, if I take 2 features and color them according to label, I obtain a plot like this, which gives intuition about the effectiveness of my features. How can I do a similar plot for ...
104 views

Speed of prediction: neural network vs. random forest?

I'm currently trying to improve on a classifier. The current method used is a neural network, and the method I've found to be better is a random forest (or even just a single tree). With 40 trees, the ...
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Are there online repositories of trained classification models? e.g. Conv-nets

I am quite new to machine learning, and I am curious as to whether other developers publish their trained classifiers (with trained weights) online for others to test out and use. I know there are a ...
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Matlab warning “linear inequality constraints active” when fitting ARMA(p,q) - GARCH(1,1)

With Matlab, I specified 9 ARMA(p,q)-GARCH(1,1) models and fitted all of them to monthly return data (I used GARCH(1,1) for every model but changed the ARMA order). Here is a very small example ...
59 views

Why would I use any MC technique other than basic sampling

I'm trying to learn sampling techniques. Lots of tutorials say that they are useful when "you can't sample directly from the pdf...." q1) If I have the algebraic form of the pdf can't I always sample ...
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How to perform multiclass SVM classification using k-fold cross-validation and SMO with some kernel method in MATLAB?

I have data matrix X.csv file of size nxd, where n are the observations, and d variables. There are c_1,..., c_m classes. Let, Y be the matrix containing the class labels. There is no header row in ...