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I realized that derivatives are linear

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Re: I realized that derivatives are linear

#5
The derivative is a linear operator, but it's not a bounded operator. That is, for example, the vector norm of f(x) = k·sin(x/k) → 0 when k→0, but the norm of d/dx f(x) does not. This also means that it's not continuous.

Of the mappings between vector spaces, the most well behaving are the bounded linear operators, and the derivative doesn't belong to these. But yes, it's linear.

Edit: Originally wrote f(x) = k·sin(k·x), but meant f(x) = k·sin(x/k).

Re: I realized that derivatives are linear

#8

This is why you take linear algebra and calculus before doing machine learning.

On the contrary - ML is a great motivator to finally grapple the "prerequisites".

During school I never understood what the math was for, so my unconscious brain never saw the necessity to actually learn it. Now I want to learn - with hugely better results.

This mechanism should be utilized much more often instead of shoving seemingly unrelated knowledge into peoples ears without letting them feel the need for it first.

Re: I realized that derivatives are linear

#10
post #9

Well this is the whole point of derivatives (i.e. tangent maps): to be linear approximations of functions. So yes, a linear approximation of a linear function is the function itself.

You are right, but what you are saying has nothing to do with the author's point: what he is saying is that the differentiation operator itself is linear, which is a meaningful and true fact even in spaces where you have no idea of what a linear function is.
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