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Questions tagged [non-linear]

60 questions
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How to include adjustable parameter in fsolve?

I'm getting familiar with fsolve in Python and I am having trouble including adjustable parameters in my system of nonlinear equations. This link seems to answer my question but I still get errors. Below is my code: import scipy.optimize as so …
t.o.
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Plot output of non-linear model output in ggplot2

I have some data where the best fitting non-linear regression is the S curve model. I want to plot the S curve in ggplot2 but do not know how to specify this model. I assume I should use the following code but do not know how to specify the method…
SoCo
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Finding multiple solution for nonlinear ode?

I am trying to compose a MATLAB code to solve for roots using fsolve for nonlinear ODE. While trying to find the solutions for these two equations at steady state, I only obtain one solution. Is there a method of obtaining all possible steady state…
ChemE Student
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D3 different zoom factor on each axis

I am trying to figure out how to create different zoom factors on the X- and Y-axis in d3. It seems to be created with a single zoom-factor for both axis, and basically I would like to know if there is a way to separate them. The basics is simple…
PelPhp
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How to set up a non-linear mixed effects model for nested plots in R using nlme function?

I want to fit a model to predict the ring density from cambial age. I have data from the nested design; two sites, four thinning treatments in each site with 5 replications (4*5 plots), and 4 tree classes in each plot. So, I want to fit a nonlinear…
Forester_Dipak
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Why are drm() predictions completely different when two outliers present?

I am using the drm() package to fit dose-response curves. I get an unexpected linear result from one dataset that has a classic sigmoid shape that should be a great fit. When I remove two outliers, drm() fits well. When I code non-linear regression…
Hannah
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multivariable curve fit python

import pandas as pd import math import numpy as np from scipy.optimize import curve_fit L_data = np.array([0.856, 0.451]) t_data = np.array([0.398, 0.507]) y_data = np.array([0.63, 0.5]) def model(x, c1, c2): x = ([L, t]) return ((480 / c2) *…
Zack
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How to make script run more efficiently "Modified Baek and Brock Nonlinear Granger Causality Test in R"

I am trying to implement the test propesed by Hiemstra and Jones (1994) for nonlinear granger causality test between two time series xt and yt. I am struggling to find any relevant packages or similar forum discussions on the topic. The paper:…
beishunter
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Non-linear equations in Cplex

I have 2 non-linear equations as below. How can I present these equations in Cplex? Thanks in advance. Q_rsp"=Q_rsp'*(exp(-lamda * t_tht)) deltaQ_rsp=(Q_rsp' - Q_rsp")*y_rsp with lamda=.25; Q_rsp'=100; y_rsp: boolean t_tht: time
Jess
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using lsqnonlin for parameter optimization but the plot it gives has wrong initial value

I'm trying to use Nonlinear Data-Fitting and lsqnonlin in Matlab to find parameter (a) of my equation. The code doesn't have any error but the plot which Matlab is suggesting, starts at a different initial value than the points I have so I can't…
Mobina Danesh parvar
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Connect a python tkinter progressbar to non-linear absolut values via function

I am looking for a function that dynamically calculates the progresbar of a python tkinter GUI. The special thing about it is, that the values to be displayed with the percentage of the progressbar are non-linear. 100% should be absolut value 50 0%…
Gymknopf
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Gradient descent self code: loss increasing gradually while optimizing -python

I'm trying to estimate the two parameter of the following exponential decay. but the error(loss) is gradually increasing. I tried smaller learning_rate, from 10 ^-2 to 10 ^-10 calculate differential again, tried with different data set. The…
user20988246
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Dynamic lower/upper bound of Pyomo Variable for every iteration

I want to adjust the lower and upper bound of three pyo.Var() depending on the outcome of another variable. the variable model.inverter_power should be in the i-th iteration bigger than model.inverter_power[i].lb + model.fcr_power[i] but also…
Lars K
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Applying a non linear ARX model in matlab

I estimated parameters of a non- linear arx model with the system identification toolbox in matlab. I was wondering how I can use these results as a function or maybe directly on other inputs. So basically I want to call my arx model function and…
Fibaro
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non-linear colour plot using filled.contour in R

How can one plot a global map using filled.contour with non linear sequences of the colorbar? If this is cannot be done with filled.contour, then how to do it with ggplot2? Thanks
Maher
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