# Category Archives: Uncategorized

## Variance and the sum of squared pairwise differences

The variance of a set of values is usually expressed in terms of squared differences between those values and the mean of those values. However the sum of squared differences between the values and the mean can also be expressed … Continue reading

## All length-preserving matrices are unitary

I recently read the (excellent) online resource Quantum Computing for the Very Curious by Andy Matuschak and Michael Nielsen. Upon reading the proof that all length-preserving matrices are unitary and trying it out myself, I came to believe that there … Continue reading

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## Linear Algebra and Its Applications, Exercise 3.4.22

Exercise 3.4.22. Given an arbitrary function find the coefficient that minimizes the quantity (Use the method of setting the derivative to zero.) How does this value of compare with the Fourier coefficient ? What is if ? Answer: We are … Continue reading