# All Questions

55 views

### Minimisation problem in thousands of dimensions

I need to find the minimum of a function (a log-likelihood from a Potts model) in tens of thousands of dimensions. The function evaluation is quite fast, takes about $10^{-3} s$, and there is a ...
11 views

### Speeding up the evaluation of a symbolic expression while retaining the precision

I have an expression DesignMatrixMult which is 2*2 matrix (in general it will be a n*n matrix). The expression is in terms of four symbolic variables q1/q2/x1/x2. ...
77 views

### Recommendations for input file format for science applications

Assuming that a program is written in either C, C++, Fortran or python, what do you think is the best format for the input file given that users could be relatively diverse, i.e. not familiar with the ...
31 views

### What is 'SOLVER' in R and Statistics/Analytics ?

**strong text**a) I tried to research on what exactly is a SOLVER only to find a not clear-cut simple answer. My doubts still remain after going through several sites full of discussions about it. I ...
19 views

### Matlab: Get the Hessian matrix using Multistart

I am using Multistart in Matlab with the fmincon command to estimate some parameters to my maximum likelihood function. The issue that I have with Multistart is ...
42 views

### Translate a 3D point along a heading

I need to translate a point (P1) in 3D a certain amount, call it stepSize, along a vector described by a heading composed of ...
76 views

### Solving Lx = b for big sparse Laplacian matrices

What algorithm is more practically suited in terms of performance for solving the $\mathbf{Lx=b}$ equation, where $\mathbf{L}$ is a generic Laplacian matrix (associated to a strongly connected graph, ...
25 views

### What is a general method for identifying how connected parts of a binary volume are?

I have a binary volume consisting of a number of disconnected objects. (coming from a noisy, anatomic dataset) However, some of the objects are 'somewhat' connected. Picture a big cylinder and a ...
26 views

### CUDA Fortran: Multi GPU Programming and memory allocation

I am writing a program that is supposed to use multiple GPUs on a single node using CUDA Fortran. Although I've looked through the Portland Group CUDA Fortran Reference, I am still unclear about how ...
21 views

### Navier Stokes Equations - Cnoidal Waves and Stokes V Waves

I am working on my undergraduate research and am trying to solve Navier-Stokes Equations for shallow water conditions. However whilst reading different implementation guides I came across the terms ...
16 views

### Modelling: How much Cd2+ will a cell be able to chelate with phytochelatins? [on hold]

I am involved in a synthetic biology project where I have to do modelling with ODEs. The biological process I want to model is the chelation of Cd2+ with phytochelatins, to know how much can be ...
42 views

2k views

### Computational Science Jokes [closed]

I've noticed some other SE sites have a canonical "what's you're favorite joke" question in them: Math Overflow's "Do good math jokes exist?" Cross Validated's "What is your favorite data analysis ...
26 views

### BLAS/LAPACK Non absolute sum

I need to know if there is some function in BLAS/LAPACK or some other Scientific Library that returns a non absolute sum of a vector/matrix. I've found the 'asum', but it returns only the absolute ...
107 views

### Looking for Runge-Kutta 8th order in C/C++

I would like to use Runge-Kutta 8th order method (89) in a celestial mechanics / astrodynamics application, written in C++, using a Windows machine. Therefore I wonder if anyone knows a good library / ...
130 views

### Most efficient library to diagonalize exactly large hermitian or unitary matrices

I am working on a physics problem which requires obtaining the exact eigenvalues and eigenvectors of Hermitian and Unitary matrices numerically. Naturally I would like to ask the experts what are the ...
41 views

### Maximum function evaluation with NLOPT in Python

I am having an issue with the implementation of NLOPT in Python. My objective is to minimize a somewhat complicated Maximum Likelihood function. My function is called mle and there are 6 parameters ...
209 views

### How to plan & incorporate project management tools into research code

I'm entering my 3rd year of my PhD program, and up until now my research code (numerical inverse problems/medical imaging/image processing/etc) consists mostly of disorganized MATLAB scripts and ...
68 views

### Numerical minimization of scalar-valued function in 3d

I am finding minimum of the potential function $f=f_1+f_2$, where $f_i: \mathbb{R}^3\to\mathbb{R}$. I was about to use Levenberg-Marquardt as the quick starting point, since it is already implemented ...
19 views

### Printing a plot in Octave-3.8.1 breaks LaTeX labels [closed]

Since upgrading to Octave 3.8 I have been unable to export plots with LaTeX labels. When the figure is displayed the labels render fine but when I try to export the figure using the ...
96 views

### Finding optimal velocity profile using Dynamic Programming

While continuously reading about Dynamic Programming I have a problem, implementing it in a practical application. Let's assume we want to optimize our way to school which we go daily by bicycle. ...
74 views

### Measurement error library

Is there a python library that would keep track of uncertainty in measured data? i.e. if I put in a figure of a±b is there an easy way to track the propagation of error through calculations.
I get a distance map output after using a Fast Marching Method. The PDE involved is the Eikonal equation which take the form : \begin{cases} c(x).|\nabla u| =1\\ u(x) =\phi(x) ...