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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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Need help plotting this function in Matlab

I recently started using Matlab and I am trying to plot Imaginary part of a function. I can see I am making a mistake somewhere because I have the graph showing what I need to get and I am getting something else. Here is the link of the graph that I…
user2768562
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Removing variables resulting in singular matrix in R regression model

I've been using mnlogit in R to generate a multivariable logistic regression model. My original set of variables generated a singular matrix error, i.e. Error in solve.default(hessian, gradient, tol = 1e-24) : system is computationally singular:…
Max
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pluralize and singularize for spanish language

sorry for my english... I have a rails application developed to spain, therefore, all content is in spanish, so, I have a search box to search in a mysql database, all rows are in spanish, I'd like to improve my search to allow to users to search…
el_quick
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nls singular gradient matrix - fit parameters in integral's upper limits

I am trying to make a nls fit for a little bit complicated expression that includes two integrals with two of the fit parameters in their upper limits. I got the error "Error in nlsModel(formula, mf, start, wts) : singular gradient matrix at…
LauraT
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Singular or Plural setting to a variable. PHP

There are a lot of questions explaining how to echo a singular or plural variable, but none answer my question as to how one sets a variable to contain said singular or plural value. I would have thought it would work as follows: $bottom="You have…
Thomas Clowes
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How to iterate complex numbers on the Riemann sphere in Maxima CAS?

I try to iterate complex numbers ( also inf and zero) in Maxima CAS I use rational function and it's derivative The only one attracting cycle is the period 3-cycle consisting of the points 0, −1, and infinity. kill(all); display2d:false; ratprint :…
Adam
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Instability of nonlinear mixed effects (using nlme package) in R

I am attempting to build a nonlinear mixed effects model for COVID-19 data that fits a bell curve to daily case numbers from different countries (random effects being at the country level). The data table is too large to include in the post but here…
bob
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Simulation terminated because derivative is not finite

I encounter this error when I try to run my Simulink application. Derivative of state '1' in block 'proiect/Filtru/Integrator' at time 9.6046876340724416E-7 is not finite. The simulation will be stopped. There may be a singularity in the solution. …
user10740425
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Humanizer fails to singularize or pluralize an italian word in C#

I have managed to singularize/pluralize an English word using Humanizer, but when I set the CultureInfo to Italian, it just adds an extra 's' to the word. For example: "Man".Pluralize() => "Men" ----- correct, It works as…
Lorenzo Goldoni
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Plural and Singular terms in PHP

I am doing an amount of users check for our website, below is the code. How can i use the word "user" if there is only 1 account and how can i use "users" if there is >1. code: $result = mysql_query("SELECT * FROM users WHERE…
AAA
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solve() crashes when aimed at singular matrices

I am trying to solve a system of linear equations in the least-squares-style. Using armadillo and its solve function I want to calculate the three coefficients of a parabolic fit. vec coeffs = solve(CtC, Ctb) with CtC= 1.0e+009 * …
bogus
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Handle Ruby on Rails resource when the singular is also plural?

Whats the best way to handle a singular resource, that itself is plural. For example a "settings page", that displays a selection of different settings. As I am displaying a single "Settings" instance, I would expect to use the show action, but…
dangerousdave
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Boundary (singular) fit in lmer

I know this error has already been issued in stackoverflow, but the solution for the other questions doesn't seem to apply to my problem. I have a very simple model that predicts energy expenditure based on the number of days. a<-lmer(energy ~ days…
JMarcelino
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ODE boundary value problem with singularities

Here is a relatively simple boundary value problem solved with shooting method and Python import numpy as np from scipy.optimize import fsolve from scipy.integrate import odeint import matplotlib.pyplot as plt %matplotlib inline R = 0.5 ka = 6.4 De…
Radovan Omorjan
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Visreg for GLM in R: singular matrix 'a' in 'solve' Error message

I'm fairly new to R but have so far been managing to use it for my master's thesis. Having run the following GLM: M1 <- glm.nb(abundance ~ temp * fseason * fperiod * fregion + offset(LogRSize) + offset(LogPLength) +…
Matt Livesey
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