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Questions tagged [singular]

Singularity is a mathematical term indicating an undefined point on a set (function). Singularity arises in many mathematical optimization problems with many variables.

An example of singularity is the derivative of the absolute value function |x| at x = 0.

Singularity arises in many ill-posed problems

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Fixing the singularity of a function

Assume you have a function like F = lambda x: sin(x)/x Evaluating F(0.0) would result in a divide by zero warning, and would not give the expected result of 1.0. Is it possible to write another function fix_singularity that would give the desired…
D R
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solving a singular matrix

I am trying to write a little unwrapper for meshes. This uses a finite-element-method to solve for minimal linear stress between flattened and the raw surface. At the moment there are some vertices pinned to get a result. Without this the triangles…
Lo L
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"system is computationally singular" error when I use 'winsorize'

I am going to winsorize my dataset to get rid of some outliers with the package robustHD. It is the first time I ran into this error. The dataset contains 50+ variables and 100+ observations. How can I fix this? And why matrix singularity matters…
lsl__
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Assignment of a Singular Iterator

A "Singular Iterator" is defined as an: iterators that are not associated with any sequence. A null pointer, as well as a default-constructed pointer (holding an indeterminate value) is singular My question 1 would be: Is a default constructed…
Jonathan Mee
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Pseudo inverse (SVD) of a singular complex square matrix in C/C++

Singular complex matrix is 2n x 2n where n is 3; 4 or 5. How to calculate Singular Value Decomposition in C/C++? Input matrix R is in the form Y*Y' where ()' is transjugate. Eigenvectors in U are the main output. Consider following Matlab…
renonsz
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In python numpy least squares, why a singular normal matrix does NOT raise LinAlgError?

Solving A.X = B by least squares. Given this : import numpy as np A=[[1,0],[0,0]] B=[1,0] X=np.linalg.lstsq(A, B) # X = 1/(At.A) * (At.B) print X[0] # [ 1. 0.] At.A is A, and det(A)=0 --> singular. So there is an infinity of solutions; [1,0]…
Eric H.
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system is computationally singular: reciprocal condition number = 1.59968e-21

I use R to calculate Tangency portfolio for all the equities in SP500. The list of equity is load via python script import urllib2 import pytz import pandas as pd import numpy as np from bs4 import BeautifulSoup from datetime import datetime from…
jerry2605
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Is there a one-liner for dealing with singular/plural words in common languages?

All too often I see websites do things like 1 views, 1 days left, or 1 answers. To me this is just lazy as its often as easy to fix as something like: if(views == 1) print views + " view" else print views + " views" What I want to know is if…
eliot
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Equation is locally singular, but Jacobian is not

I have been using the Trust-Region Dogleg Method in MATLAB to solve a system of nonlinear equations: f(x)=c. However, when I change the values of the c vector to certain values, MATLAB returns that the problem is locally singular. When I outpu the…
Brian
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What causes "Jacobian matrix" to be singular in SAS?

I have a simple SAS (version 9.2) program as follows, proc model; cdf('normal',log(V/100)+1)=0.5; bounds V>0; solve V/solveprint; run; It throws exception that says jacobian matrix to be singular, The Newton method Jacobian matrix of partial…
Richard
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SSRS Report Manager rules for generating Models from Data Source with plural table names

I am using the SSRS Report Manager web interface to generate Data Models for a SQL Server 2008 R2 Data Source. The database contains a number of tables with names which are plurals. In the generated Data Models, the corresponding entities have names…
Chris Mc
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R: How to solve Lapack routine dgesv: system is exactly singular in Mahalanobis distance

I am trying to run an Explanatory Factor Analysis on my questionnaire data. I have data for 201 participants and 30 questions. The head of my data looks somehow like this (I am showing only the first 5 questions to give an idea of the dataset…
Cristina Procentese
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fixed-effect model matrix is rank deficient so dropping 27 columns / coefficients AND boundary (singular)

Study background: I want to see if mean caterpillar abundance for a given year and within a given population, can explain differences in bird(blue tit) density. The blue tits breed in nest boxes, so I calculated density as the total number of…
cpc
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Comparing mixed models: singular fit for random effect group but only in some models. Should I drop RE group from all models or just where singular?

I am fitting several mixed models using the lmer function in the package lme4, each with the same fixed effects and random effects, but different response variables. The purpose of these models is to determine how environmental conditions influence…
Oscar Clendon
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Double numerical integration in Matlab - Singularity

I have discrete data of a 2D function defined as theta = linspace(0,pi,nTheta); phi = linspace(0,2*pi,nPhi); p=zeros(nPhi,nTheta);%only to show the dimension of my matrix [np,nt]=ndgrid(phi,theta); f1 = griddedInterpolant(np,nt,p,'spline'); f2=…
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