1% Compute Costforlinear regression2%cost Function函数实现___利用矩阵操作进行!!3function J =computeCost(X, y, theta)45%Initialize some useful values6m = length(y); %number of training examples7J =0;89%Instructions: Compute the cost of a particular choice of theta10% You shouldsetJ to the...
PS: 此处平方差公式原本应当是除以 m,这里除以 2m 只为了以后在数学上计算方便,这里除以 m 和 除以 2m 对获得最小的代价函数值没有影响。 $J(\theta_0, \theta_1)$被成为代价函数(cost function),这是回归问题中最常使用的方法. 现在要做的就是得到使 $J(\theta_0, \theta_1)$ 最小的 $\theta_0...
1%梯度下降算法实现 gradientDescent(X, y, theta, alpha, iterations) %X-training example,y-实际数值,alpha-learning rate2function [theta, J_history] = gradientDescent(X, y, theta, alpha, num_iters)34% theta =GRADIENTDESENT(X, y, theta, alpha, num_iters) updates theta by5%taking num_iters...
this is going to be my overall objective function for linear regression. And just to, you know rewrite this out a little bit more cleanly, what I'm going to do by convention
Loss function: Used when we refer to the error for a single training example. Cost function: Used to refer to an average of the loss functions over an entire training dataset. https://www.analyticsvidhya.com/blog/2021/02/cost-function-is-no-rocket-science/ ...
multiple linear regressionoutliersConsider a times series in simple linear regression. It is shown that under suitable conditions point estimates or predictions for the next time period into the future are unaffected by values of the dependent variable at some given time period in the past. The ...
4.1. Example: the Loss, Cost, and the Objective Function in Linear Regression Let’s say we are training a linear regression model: We’ll assume the data are -dimensional, and we prepend a dummy zero value to all the instances to simplify the expression. Averaging the square loss over th...
logistic regression cost function(single example) 图像分布 logistic regression cost function(m examples) Writting cost function in a more conve...
For example, let's say you own a production facility. Initially, as output increases, the business becomes more efficient at using its resources. Workers develop expertise and routines, machinery operates at more efficient levels, and fixed costs are spread across more units. During this phase, ...
We examine linear regression problems where some features may only be observable at a cost (e.g., in medical domains where features may correspond to diagnostic tests that take time and costs money). This can be important in the context of data mining, in order to obtain the best prediction...