Questions tagged [vector]

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How do I take the derivative to $\gamma $ of $(y-x^{\gamma})^T(y-x^{\gamma})$?

I have to solve the least squares for $\gamma$ in the following problem. The model is described as $y_i = \beta x_i^{\gamma} + u_i$, where $u_i $ is i.i.d. normal with mean zero and variance $\sigma^2$...
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Matrix and vectors, why different notation for dimensions?

If we collect data and put it into a matrix of size (100,3), we tend to say we have three-dimensional data. We think of each column as a dimension. On the other side, if we have a vector of size (100,...
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What is the entropy of multivariate data multiplied by a vector?

It is a general rule that for multivariate data $\boldsymbol{X}$ and a matrix $\boldsymbol{A}$, their entropy is $$h(\boldsymbol{A} \boldsymbol{X}) = h(\boldsymbol{X}) + \ln |\det \boldsymbol{A}|$$ (...
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what is the expected value of the dot product of two vectors

I have a little question, but I don't know that well how to answer it. I have a random walker with position vector $\vec{r} = \sum_{i=1}^N \vec{r}_i$, where i is the random walker's step. Every vector ...