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Questions tagged [non-linear-regression]

In statistics, nonlinear regression is a form of regression analysis in which observations are modeled by a function which is a nonlinear combination of the model parameters and depends on one or more independent variables.

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R plot with ggplot2 linear regression with a transformed dependent variable

So my problem is quite simple, I want to plot the exponential regression of my data, so far what I've done was plot the polynomial regression : ggplot(data = mydataANOVA, aes(x = TpsenJour, y = PrptionJourAuDelaDe, color = Type_Contrat))+ …
PaoloH
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Neural Networks Regression : scaling the outputs or using a linear layer?

I am currently trying to use Neural Network to make regression predictions. However, I don't know what is the best way to handle this, as I read that there were 2 different ways to do regression predictions with a NN. 1) Some websites/articles…
Paul Rolin
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Simple Orthographic Structure from Motion using R -- Determining Metric Constraints

I would like to build a simple structure from motion program according to Tomasi and Kanade [1992]. The article can be found below:…
Alex Witsil
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Why does IPOPT evaluate objective function despite breaching constraints?

I'm using IPOPT within Julia. My objective function will throw an error for certain parameter values (specifically, though I assume this doesn't matter, it involves a Cholesky decomposition of a covariance matrix and so requires that the covariance…
Wilbur
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Building a non linear model with ReLUs in TensorFlow

I'm trying to build a simple non-linear model in TensorFlow. I have created this sample data: x_data = np.arange(-100, 100).astype(np.float32) y_data = np.abs(x_data + 20.) I guess this shape should be easily reconstructed using a couple of…
prl900
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How to get initial values for fitting a Gompertz model with fixed y-intercept in nls?

I am trying to fit growth data from juvenile geese to the Gompertz model, but I would like to fix it at the y-intercept, which would correspond in this case to body mass of 72.1 for t = 0. Taking the parametization form used in SSgompertz in nls, I…
ebcs
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Julia: using CurveFit package non linear

why the code below does not work? xa = [0 0.200000000000000 0.400000000000000 1.00000000000000 1.60000000000000 1.80000000000000 2.00000000000000 2.60000000000000 2.80000000000000 3.00000000000000 3.80000000000000 4.80000000000000 …
Cientista Mirim Ciência
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Fitting non-linear Langmuir Isotherm in R

I want to fit Isotherm models for the following data in R. The simplest isotherm model is Langmuir model given here model is given in the bottom of the page. My MWE is given below which throw the error. I wonder if there is any R package for…
MYaseen208
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How should decide about using linear regression model or non linear regression model

How should one decide between using a linear regression model or non-linear regression model? My goal is to predict Y. In case of simple x and y dataset I could easily decide which regression model should be used by plotting a scatter plot. In case…
shakthydoss
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How to choose the degree of a Hypothesis function?

In a normal machine learning problem you get many features(eg:- if you are making an image recogniser), so when there are many features you can't visualise the data(you can't plot a graph). Without plotting a graph is there a way to determine what…
sachira
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Fitting data to a Boltzmann sigmoid function, and estimating parameters with a non-linear least squares fitting in R

I have a dataset of 10 subjects, whose muscle response amplitude was measured across 11 different stimulus intensities (states) applied to their muscles. The output curve of the data looks like a sigmoidal function, with different stimulus…
A.R.
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Fitting complex non-linear function with nls() in R gives singular gradient error

I am trying to fit oral pharmacokinetic function using R nls. The function can be seen here: I tried the following: dat <- data.frame( Time = c(10, 15, 20, 30, 40, 60, 90, 120, 180, 210, 240, 300, 360), C_PO =…
PPenton
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I have a problem assessing my zero-inflated negative binomial model against a poisson model

I have replicated a zero-inflated negative binomial model (model 1, table 1) from the article: Scharpf, Adam. 2020. “Why Governments Have Their Troops Trained Abroad: Evidence from Latin America.” International Studies Quarterly 64 (3): 734–47.…
LauMadsen
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How to fit a small dataset with a perceptron model using Pytorch

I'm trying to fit a small dataset(just 7x1 size) with a 3-layer perceptron model, but the loss can't converge. I'm fresh to machine learning area, can someone please give me a hint to adjust my code? import torch import torch.nn as nn import…
bin Pang
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Fit double logistic function to a time series

For the following time series data: #1. dates of 15 day frequency: dates = seq(as.Date("2016-09-01"), as.Date("2020-07-30"), by=15) #96 times observation #2. water content in crops corresponding to the times given. water <- c(0.5702722,…
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