bio | website | regularize.wordpress.com |
---|---|---|

location | Braunschweig, Germany | |

age | 36 | |

visits | member for | 4 years, 10 months |

seen | Jul 29 at 8:47 | |

stats | profile views | 1,991 |

Professor at TU Braunschweig.

Area: Inverse problems, regularization theory, applied functional analysis, mathematical image processing.

Jul 24 |
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How to calculate $det(X^TX)$ efficiently, update one column of X each time
Not a good fit for this side - I suggest scicomp.stackexchange.com. Anyway: Why not do a factorization of $X_1$ (LU or QR) and down- and update that? |

Jul 24 |
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9-point stencil “equivalent” for advection equation
This question should go well on scicomp.stackexchange.com. |

Jul 17 |
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question about $TGV^2$ space
Added something on the interpretation with Radon measures… |

Jul 17 |
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Is this has anything to do with Riesz representation?
Nope, not linear since flipping the sign of my won't flip the sign of the value. |

Jul 17 |
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Is this has anything to do with Riesz representation?
One more thing: Your functional is not linear but only positively homogeneous, so what kind of result do you expect? |

Jul 17 |
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Is this has anything to do with Riesz representation?
What form of Sobolev norm are you using, i. e. how are the sup-norm of the function and it's derivative combined? |

May 20 |
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Projecting a convex partition onto a convex set
Err, sorry - of course, nonempty $X$ it should be… |

May 20 |
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Projecting a convex partition onto a convex set
$X$ could be empty or have $n-1$ points... You need some more conditions. |

May 19 |
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Splines linearly independent
What do you mean by "its unique smooth extension"? |

May 14 |
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Which way for reading the proofs?
@fanzheng I heard a similar quote about a famous optimizer "I don't read papers, I write them." |

Apr 23 |
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l1 Quadratic Programming
Noting that the above problem has all these guys as variables: Isn't that in standard for already? |

Apr 23 |
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A question involving Mazur's Lemma
Well, the degenerate case $y_n = x_n$ does not work so some assumption on the convex combination is needed. |

Apr 14 |
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2, 3, and 4 (a possible fixed point result ?)
As far as I understood, the BGK (Browder-Göhde/Göbel-Kirk) fixed point theorem states that every non-expansive self-mapping on a non-empty, closed and convex subset of a uniformly convex Banach space has a fixed point. |

Mar 27 |
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Hadamard / matrix product adjoint
Ok, I see now. I think a better fit for this question would be scicomp.stackexchange.com. Anyway: The adjoint is defined by $\langle A^* y,x\rangle = \langle y,Ax\rangle$. You do adjoints one by one from outside to inside. |

Mar 26 |
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Hadamard / matrix product adjoint
Sorry, but this does not make sense. What is the Hadamard product of the matrix S and the vector Fx? |

Mar 26 |
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Hadamard / matrix product adjoint
Err... So x is a matrix? |

Mar 26 |
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Hadamard / matrix product adjoint
I could not parse your definition of the operator A. If D and S are matrices, do you build the Hadamard product with the matrix of the Fourier transform? |

Mar 26 |
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Convergence in energy of bounded (semi)subharmonic functions
Sorry for the late reply: I guess the best thing would be to write an answer yourself so that this is kept for the records. |

Mar 17 |
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Fredholm integral with functions constrained to [0;1]
For some reason I confused $g$ and $f$. Of course $f$ should be the unknown… Corrected. |

Mar 16 |
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Fredholm integral with functions constrained to [0;1]
The most simple thing that comes to mind is the projected gradient method, see my update. |