# Questions tagged [matrix]

A matrix is a collection of numbers arranged into a fixed number of rows and columns.

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8 views

### RNN components in neural network [closed]

what does parametric matrix do in RNN, p = softmax(W*s),what is role of W here
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### How to compute Hessian matrix for log-likelihood function for Logistic Regression

I am currently studying the Elements of Statistical Learning book. The following equation is in page 120. It calculates the Hessian matrix for the log-likelihood function as follows But is the ...
16 views

### Why don't the dimensions in this linear regression equation match up?

I'm going through an article on linear regression, and they give the following formula for computing estimates: The convention is that all vectors are column vectors. So if ...
74 views

### tensorflow pseudo inverse doesn't work for complex matrices!

The Tensorflow documentation here says that: tf.linalg.pinv is ''analogous to numpy.linalg.pinv. It differs only in default value of rcond''. However, tf.linalg.pinv requires the matrix to ...
17 views

### Recommender system that matches similar customers with similar highly rated products?

I have a dataset of 1,000 customers that bought 20 distinct phones and rated them 1-5. I have several demographic attributes for these customers (gender, age). My website offers 100 distinct devices, ...
30 views

### Scipy Sparse vstack memory error

I have a bunch of scipy matrices (of the same #columns) loaded from disk. I want to combine them into one scipy sparse matrix. I am using scipy sparse vstack method. I am able to load the ...
18 views

### Correlation between numeric variables of different meaning

I have a data set containing information about buildings, such as the area code, the neighborhood code, the number of floors, the year in which the house was built and the year in which restorations ...
12 views

### Question regarding: Vectorization Math of Backpropagation in a Neural Network

Formula: These are the formula I use for backpropagation from Brilliant: Question: If we consider a Neural Network with the structure (3,2): And we would start calculating the derivative (for 1 ...
40 views

### List of Correlations to Correlation Matrix [closed]

I am using python to do some data analysis and I need to represent the following table as a correlation matrix. The correlation value is a value between -1 and 1. ...
121 views

### Normalize / Standardize in a Random Forest?

If I have a matrix of co-occurring words in conversations of different lengths, is it appropriate to standardize / normalize the data prior to training? My matrix is set up as follows: one row per ...
22 views

### Matrix multiplication doesn't work - no output

I am having problem in the Matrix multiplication of my Python neural network. Being still a High schooler, I know next to nothing about MM except a couple of tutorials. My Neural network was working ...
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### Binary Matrix Factorization: Regularizer to encourage 1-0 matrices

I have the following problem: Given a (user, access rights) binary matrix, I need to find the best (user, role) x (role, access right) binary matrices to reconstruct the original matrix. The current ...
19 views

### Linear Regression Error in feature matrix step

I'm trying to code the design function used in linear regression using numpy and I get this error: Traceback (most recent call last): File "C:\Users\visha\AppData\Local\Continuum\anaconda3\lib\...
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### One hot encoding of continuous floats using keras backend

I am trying to convert a vector of floats into a matrix similar to one hot encoding, but I want this to happen in non-discrete space to retain gradients. Therefore I am only able to use keras backend ...
390 views

### How do I generate a laplacian matrix for a graph dataset?

If I have a dataset in a csv that looks like the one shown below. How do I convert this into a laplacian matrix using Python?
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I have a $(418,2)$ matrix and I want to convert it to csv. so I write: np.savetxt('titanic1.csv', Sol, fmt='%.2f', delimiter=",",header="PassengerId,Survived") ...
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### Transformation of matrix with missing values for hierarchical clustering

Comparing different variables, I got a matrix with lots of missing values. How do I have to transform the matrix below for hierarchical clustering? What I have already tried: ...
2k views

### Calculating cosine similarity between 3D arrays using Python

I have two matrices with multiple columns and three rows each. I calculated the cosine similarity (sklearn) but it gives the result as a matrix. How can I obtain one single value? The matrices are the ...
84 views

### Is there a difference between np.matrix(np.array([0,0])) and np.matrix([0,0])?

I was reading this code, for implemnting linear regression from scratch: ...
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### Issue in computing matrix inverse

I need to compute inverse of a matrix that has very small values of the range of 10^-9. When I use numpy.linalg.inv it gives all entries of the inverse matrix as 0. I checked in the original matrix ...
19 views

### Is this an incorrect way of back-propagating error with matrices?

I was watching a public available video from Stanford (https://youtu.be/d14TUNcbn1k?t=2720) on the mathematics behind back propagation. They proposed a graph: that was then used as an example of back ...
415 views

### Computation of kernel matrix using radial basis kernel in svm

I want to compute a kernel matrix using RBF on my own. The training data is multidimensional. My query is whether we will apply $$e^{-\gamma(x-y)^2}$$ for each dimension and then sum the values across ...
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### How does on test regression for a subspace or matrix factorization?

I've recently been reading a lot of papers and watching a lot of videos on both subspace learning, and matrix factorization. One thing is particularly eluding me though - how does any of this get ...
44 views

### Having difficult interpreting the eigenvectors for a simple 3x2 matrix

I calculated the eigenvectors and eigenvalues from a covariance matrix given a data matrix of 3 columns and 2 rows. I am trying to interpret results but I can't understand on how to interpret them. ...
965 views

### Python memory error: compute inverse of large sized matrix

I have a big matrix of size 200000 x 200000. I need to compute its inverse. But it gives out of memory error on using numpy.linalg.inv. Is there any way to compute the inverse of a large sized matrix.
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### How do I find output size of a network?

The input to a convolutional layer of a neural network is an image of size $128\times 128\times 3.$ $40$ convolutional filters of size $5\times 5$ are applied to it. Would you get an output? If no ...
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### Faster 3D Matrix Operation - Python

I am working with 3D matrix in Python, for example, given matrix like this with size of 2x3x4: ...
201 views

### How are weights calculated in a feed-forward neural network before they are summed up with bias?

I have read a lot of papers and watched different videos, it seems like they explain how they are summed up with bias before entering the activation function. What I am trying to understand is the ...
187 views

### how exp(-z) is working in a sigmoid function in neural networks while z is a matrix?

function g = sigmoid(z) %SIGMOID Compute sigmoid function J = SIGMOID(z) computes the sigmoid of z.% g = 1.0 ./ (1.0 + exp(-z)); end i'm going through andrew ng coursera course i have a doubt ...
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### Is this matrix correctly built?

I was reading an article called "Ensemble learning in recommender systems: combining multiple user interactions for ranking personalization" where they explain a method they use called "BPR ...
121 views

### How can I create convolutions or linear layers that operate on vectors rather than scalars in pytorch?

Consider an nn.Linear(2,3) layer transform like the one below. It uses a 2x3 matrix of scalar weights to create a weighted sum for each scalar element in the ...
449 views

### How can I perform backpropagation directly in matrix form?

I had made a neural network library a few months ago, and I wasn't too familiar with matrices. So, instead of performing matrix dot products (between weights and inputs, then adding a bias matrix), I ...
42k views

### Normalize matrix in Python numpy

I've an array like this: ...