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location Barcelona, Spain
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visits member for 1 year, 5 months
seen Dec 20 '13 at 2:12

Aug
1
accepted Derivative of $f(x) = a \sum_{i=1}^x 10^{x-i}$
Aug
1
comment Derivative of $f(x) = a \sum_{i=1}^x 10^{x-i}$
@anorton Exactly.
Aug
1
comment Derivative of $f(x) = a \sum_{i=1}^x 10^{x-i}$
@GeorgeV.Williams I don't think $g(x)$ is unique. Does it have to be unique for the problem to have a solution?
Aug
1
comment Derivative of $f(x) = a \sum_{i=1}^x 10^{x-i}$
To put it in different words, I want to find $g'(x)$ where $g(x)$ is a differentiable function such that $g(x) = f(x)$ $\forall x = \{x \in \mathbb{N} | x > 1 \}$.
Aug
1
asked Derivative of $f(x) = a \sum_{i=1}^x 10^{x-i}$
Nov
4
awarded  Scholar
Nov
4
accepted How to undo linear combinations of a vector
Nov
4
awarded  Supporter
Nov
4
comment How to undo linear combinations of a vector
@GerryMyerson Sorry for using an nonstandard presentation for the problem. So, basically I have to solve a system of equation with potentially redundant equations.
Nov
4
comment How to undo linear combinations of a vector
Least squares does indeed work, but not always because $A^{T}A$ may be singular. There is no particular reason I'm using row vectors.
Nov
4
awarded  Student
Nov
4
asked How to undo linear combinations of a vector