# Alexis Alulema

## Cholesky Decomposition for Linear Regression with TensorFlow

Although Linear Least Squares Regression is simple and precise, it can be inefficient when matrices get very large. Cholesky decomposition is another approach to solve matrices efficiently by Linear Least Squares, as it decomposes a matrix into a lower and upper triangular matrix (L and LT). Finally, linear regression with Cholesky decomposition...

## Linear Least Squares Regression with TensorFlow

Linear Least Squares Regression is by far the most widely used regression method, and it is suitable for most cases when data behavior is linear. By definition, a line is defined by the following equation: For all data points (xi, yi) we have to minimize the sum of the squared...

## Classification Loss Functions (Part II)

In my previous post, I mentioned 3 loss functions, which are mostly intended to be used in Regression models. This time, I’m going to talk about Classification Loss Functions, which are going to be used to evaluate loss when predicting categorical outcomes. Let’s consider the following vector to help us...

## Loss Functions (Part 1)

Implementing Loss Functions is very important to machine learning algorithms because we can measure the error from the predicted outputs to the target values. Algorithms get optimized by evaluating outcomes depending on a specified loss function, and TensorFlow works in this way as well. We can think on Loss Functions...

## Activation Functions (updated)

Table of Contents What is an activation function? Activation Functions Sigmoid ReLU (Rectified Linear Unit) ReLU6 Hyperbolic Tangent ELU (Exponential Linear Unit) Softmax Softplus Softsign Swish Sinc Leaky ReLU Mish GELU (Gaussian Error Linear Unit) SELU (Scaled Exponential Linear Unit) What is an activation function? An activation function is a...

## Working with Matrices in TensorFlow

Matrices are the basic elements we use to interchange data through computational graphs. In general terms, a tensor can de defined as a matrix, so you can refer to Declaring tensors in TensorFlow in order to see the options you have to create matrices. Let’s define the matrices we are...

## Understanding Variables and Placeholders in TensorFlow

Usually, when we start using TensorFlow, it’s very common to think that defining variables is just as trivial as a HelloWorld program, but understanding how variables (and placeholders) work under the hood is very important to understand more complex concepts because those concepts heavily use variables/placeholders; and, if we don’t...

## Declaring tensors in TensorFlow

[Requirement: Tensorflow and NumPy installed on Python +3.5][Requirement: import tensorflow as tf][Requirement: import numpy as np] Tensors are the primary data structure we use in TensorFlow, and, as Wikipedia describes them, “tensors are geometric objects that describe linear relations between geometric vectors, scalars and other tensors”. Tensors can be described...