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1
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1answer
133 views

Creating an animated graph model based on equations

So I have a graph that looks like this ...
2
votes
1answer
189 views

Model fitting to noisy data with a custom minimization function

I'm looking into fitting some data with Mathematica. I've got my head around how NonlinearModelFit works (I've been using the Levenberg-Marquardt algorithm for some ...
0
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4answers
132 views

RSolve fails on a two-equation non-linear system

I have a system of just two recurrence equations, I need to solve them and so I use RSolve: ...
0
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0answers
33 views

How does one use StandbyDistribution to model the reliability of an M of N warm standby system when M > 1?

I am modeling the reliability of a system with four units, numbered 1 through 4. The system needs at least two of the four units to be operational. Initially units 1 and 2 are active and units 3 and ...
0
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0answers
41 views

Write nth line to file [duplicate]

I have a code that I am running on a supercomputer. Currently the algorithm must finish before I can export any results from the algorithm. What I would like to do is to have the algorithm write out ...
1
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0answers
160 views

Non linear model fit mathematica

I want to fit experimental data (temp,alpha) to the following equation for calculating k and Ea -Log[alpha]^n = function(k,Ea,temp) However i do not know ...
2
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1answer
103 views

LinearModelFit of WeatherData

I am trying to perform a linear regression on some weather data, but I can't seem to figure out how to perform the operation. What I have right now is this: ...
1
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1answer
97 views

In a manipulatable graph, display x values of all intersections with one of the lines?

I'm doing a project about Moore's law, I'm trying to create a graph that which you can manipulate, but I want the x-values of the intersections with one the lines to be displayed; how would I go about ...
0
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0answers
93 views

Making a predictive statistical model

I am totally new to Mathematica, and I have never used a similar program, apart from perhaps Excel (and I didn't even use Excel on a professional level). So I want to create a mathematical model ...
4
votes
3answers
237 views

Approximate minimum degree permutation algorithm in Mathematica

In MATLAB there is a nice implementation of the so called AMD (approximate minimum degree permutation) algorithm named amd (see Online MATLAB Documentation). There is an alternative algorithm called ...
7
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1answer
320 views

How does Mma compute Confidence Intervals?

I am trying to understand how Mma computes the Confidence Intervals after a NonlinearModelFit. Consider the following example: ...
3
votes
1answer
216 views

Modelling the effect of a structure on a “tsunami” (hyperbolic wave equation)

So, the hyperbolic wave equation can be quite easily solved in Mathematica like this: ...
6
votes
1answer
457 views

Modelling a Rocket Launch using NDSolve

I'm trying to model a rocket launch with Mathematica but I've run into a little problem since I don't know how to turn the thrust off. I'm using Newton's Law of Universal Gravitation plus an added ...
0
votes
3answers
186 views

Given a Boolean representation of a system, how can the Reliability Function be displayed as symbolic algebra?

Can Mathematica 9 convert a Boolean representation of an RBD to its symbolic algebraic form? If I have a simple series Reliability Block Diagram made up of 2 components, c1 and c2 bexpr1=And[c1,c2] ...
3
votes
1answer
166 views

ParametricNDSolve and Constraint satisfaction problem

I am trying to find the values of two parameters that allow for a specific result of my differential equations, under different initial conditions. Given a system of equations: ...
1
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0answers
93 views

Can we ask ComponentMeasurements to use NonLinearModelFit to return a covariance matrix for underlying intensity data?

I'd like to be able to calculate a covariance matrix for some data underlying a morphological component. Provided this data, I can write something like: ...
0
votes
1answer
116 views

How to simulate a multivariate recursive system from a list

New to mathematica, trying to use Eric Swanson's Pertubation AIM program to solve DSGE models. His code produces a solution as a list or a table. My question is how do I use this list to simulate the ...
3
votes
1answer
349 views

Generating a “best fit” curve to a set of noisy data corresponding to a moving object

Please note that this is an extension of a previous question: Interpolating a sparse list of two-dimensional coordinates We have an ordered array of coordinates corresponding to the position of an ...
5
votes
1answer
386 views

Plot two functions within manipulate

I just want to plot all stochastic processes and their average process. The original code without the average is: ...
0
votes
1answer
85 views

Solving one equation, then inputting the values into another for NonlinearModelFit

Considering the equation a*x^3 + a*x^2 + x + b == 0 I'm looking to find the best value for a and ...
2
votes
4answers
281 views

Problem with WhenEvent

I am trying to add a time dependent fraction to a parameter in NDSolve, i.e. when 10 < t< 20, add ...
3
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2answers
288 views

How do I represent a system dynamics feedback loop?

In System Dynamics, if I want represent the relationship between Speed and Distances, I create a Flow (Speed) and a Stock (Distance) as you can see in this Insight Maker Sample . Heres an Image of how ...
13
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4answers
1k views

Mathematica Implementations of the Random Forest algorithm

Is anyone aware of Mathematica use/implementation of Random Forest algorithm?
10
votes
3answers
347 views

Sinusoid modelling

There are lots of great demonstrations that show how to get periodic functions in the unit circle. I'm wondering how hard it would be to simulate a "moving grid" similar to this video on youtube ...
10
votes
2answers
391 views

What's the analogue of UML in Mathematica land?

What's the analogue of Unified Modeling Language (UML) in Mathematica land? Mathematica has elements of object-orientation, but most Mathematica programs or applications aren't of object-oriented ...
6
votes
1answer
786 views

Mathematica Package for Bayesian Networks

Are there any packages that allow the simulation of Bayesian Networks with Mathematica? I found what seemed to be a promising package (Dynamics) on a Brown University URL, ...
14
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3answers
502 views

How to perturb a Dynamic System?

I'm trying to model a basic feedback system with delayed feedback. I've done the initial setup and now want to add a few more advanced features to my system. Currently, it's just a simple ...
2
votes
2answers
447 views

How to model Macroeconomic dynamics?

I am rather new to Mathematica and I wanted to see if I could get some help with the following. I am trying to generate a model of macroeconomic indicators defined by the following functions, but I ...
5
votes
0answers
219 views

Second-Order Feedback Pathways

I'm relatively new to Mathematica and I've tried searching and reading through the Mathematica documentation but I'm not able to find a good place to start. I want to model a simple, second-order ...
2
votes
1answer
372 views

PlotRange problems

I have a Delay Differential Equation of the form: ...
6
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0answers
369 views

Sensitivity Analysis: Global Sensitivity and Screening

I have a model which accepts several input parameters and now I want to study the sensitivity to certain parameters as described in here: Cross Validated Answer and in Wikipedia. There is also a link ...
12
votes
3answers
2k views

How to do System dynamics simulations / diagrams in Mathematica?

System dynamics is an approach to understanding the behaviour of complex systems over time. It deals with internal feedback loops and time delays that affect the behaviour of the entire system. What ...