Computational Science Weekly Newsletter - Tuesday, July 29, 2014

Computational Science newsletter

Top new questions this week: Understanding the cost of adjoint method for pde-constrained optimization I'm trying to understand how the adjoint-based optimization method works for a PDE constrained optimization. Particularly, I'm trying to understand why the adjoint method is more efficient for … optimization pde   asked by Paul 5 votes answered by Geoff Oxberry 6 votes Discrete Poisson Equation with Pure Neumann Boundary Conditions I'm trying to implement the Helmholtz-Hodge Decomposition in 2D, which states that a vector field is composed by a rotational free component, a divergence free component and a harmonic component. … finite-difference boundary-conditions discretization poisson   asked by pceccon 4 votes answered by Truman Ellis 2 votes Numerically compute one-to-one mapping I have a set of points defined by their coordinates $(x_1,y_1)$ after changing some parameters of the problem I obtain a second set of points defined by their coordinates $(x_2, y_2)$. There exists a … algorithms nearest-neighbors   asked by OSE 4 votes answered by Kirill 2 votes Cloud solutions for microscopy image analysis At our research facility we routinely perform what are called PALM (Photo-activated localisation microscopy) or STORM (stochastic optical reconstruction microscopy) experiments. You can read all … image-processing data-management cloud-computing   asked by Kris 3 votes answered by meawoppl 3 votes Pre calculate mathematical expressions in Fortran 90 Is there some flag to let the Fortran compiler pre calculate a math expression before compiling it?. I have to write expressions that contain many small 4x4 matrix multiplications. The thing is, most … optimization fortran   asked by Michael 2 votes How to minimize the artefact of a cartesian to polar transform followed by a polar to cartesian transform? I'm transforming cartesian images into polar images. (x,y) => (angle, radius) I fill the polar image by iterating on each of its pixels and filling them by doing the reverse polar transform. For a … algorithms c++ interpolation image-processing   asked by Master of the Elephants 1 vote answered by Aurelius 1 vote Greatest hits from previous weeks: Which algorithm is more accurate for computing the sum of a sorted array of numbers? Given is an increasing finite sequence of positive numbers $z_{1} ,z_{2},.....z_{n}$. Which of the following two algorithms is better for computing the sum of the numbers? s=0; for \ i=1:n s=s … algorithms floating-point   asked by CryptoBeginner 11 votes answered by gnasher729 3 votes Fastest PCA algorithm for high-dimensional data I would like to perform a PCA on a dataset composed of approximately 40 000 samples, each sample displaying about 10 000 features. Using Matlab princomp function consistently takes over half an hour … high-dimensional data-analysis   asked by mellow 9 votes answered by Alexander 8 votes

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