Questions tagged [scientific-computing]
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scientific-computing
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Gaussian Matrix?
Does a "Gaussian Matrix" refer to a matrix that has undergone gaussian elimination to become an upper triangular matrix (the U in lu factorization), or instead to the elimination matrix that ...
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Pivoted QR in Julia?
In Julia, the function qr(A) will perform a QR decomposition on a given matrix A. However, is there any function/way in Julia to do a "pivoted" QR decomposition on a given matrix?
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QR Factorization of Rank Deficient Matrix in Julia?
If (in Julia) we compute the QR factorization of a rank deficient matrix like A=[1 2 3;4 5 6;7 8 9], some of the diagonal entries of the R matrix will be very small. However, when doing this ...
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How to initialize a container struct without knowing its size?
I am an amateur in C++, I am working on an scientific computing code. I defined a struct to store all the data input from the file. In the struct I have several 2D and 1D arrays whose dimensions ...
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Diagonal Matrix of Sigma Values in Julia
If I compute the SVD of a matrix A in Julia, it will give the sigma values of the matrix, BUT NOT in matrix form. However, if I want to assemble the sigma values of a matrix A into a diagonal matrix, ...
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Efficient/parallel matrix routines on Apple silicon
I'm working in Physics, and as part of my job I have to do a lot of numerical calculations ("numerics"), 90+% of which involves the diagonalization of large matrices. At the moment, I use ...
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UnboundLocalError: local variable 'rmeff' referenced before assignment
Hey I'm trying to compute the concentration of a tubular reactor with two reaction, I get this error thrown each time I run the code, I tried putting the variable in the function as global still ...
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When to use xarray over numpy for medium rank multidimensional data?
I have some multidimensional data and was wondering if i should use xarray when speed is one, albeit not highest, of my concerns.
I have a 4D array so it's not so big as to preclude me from using ...
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How to calculate the path of a particle subject to a vortex?
I'm trying to draw a path of a particle starting at (x0,y0) subject to a vortex located at (xv,yv). This is inspired by Lorena Barba's AeroPython. As stated in the lesson, the motion should be ...
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Is there an effective way to fit the following two datasets with lsqcurvefit?
I have two complex datasets for which I intend to find a suitable function to fit them. The first dataset is presented as follows:
As you can see, although complicated, it seems that this dataset is ...
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pymc.Uniform giving ZeroProbability error: Stochastic alpha's value is outside its support, or it forbids its parents' current values
I am using a example given in web of pymc, when I try to run pymc.Uniform I am getting the following error
---------------------------------------------------------------------------
ZeroProbability ...
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Finding the best linear section of data
I have some scientific data and wish to find the best region to fit a straight line in. Theoretically, the data should have a constant gradient but other influences effect the data such that there are ...
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MATLAB: Does the execution of addpath/rmpath/savepath in one MATLAB instance affect other instances?
Does the execution of addpath/rmpath/savepath in one MATLAB instance affect other instances?
Motivation: Imagine that you are developing a MATLAB package, which provides a group of functions to the ...
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Is MEX of MATLAB known to be slow on macOS?
Question: Is MEX of MATLAB known to be slow on macOS?
Here, "slow" refers to the speed of setting MEX up, of compiling MEX code, and of running the MEX function.
I have done some timing ...
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How do I add another coordinate label in Xarray?
I have an Xarray, say
da = xr.DataArray([[1,2],[1,2]],coords={'x':['param1','param2'],'y':['idx','idx2']})
This is a 2D data array. As I build out my code, I would like to add another "column&...
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