# Questions tagged [mathematical-modeling]

A mathematical model is a description of a system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modelling.

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### Why life expectancy calculate as 1/μ in SIR model?

In the SIR model, when the death rate is μ, life expectancy is calculated as 1/μ. Can anyone explain it intuitively?
24 views

### Initial margin covariance matrix [closed]

I am trying to replicate the following example in order to calculate IM : https://www.clarusft.com/isda-simm-in-excel-equity-derivatives/?amp=1 I am stuck at the last step (impossible to find the ...
1 vote
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### What is the physical and mathematical meaning of nonsymmetric mass, damping and stiffness matrix of a linear fluid-solid interaction modeling problem?

Suppose the problem of the subsonic flow over a simply-supported rectangular plate as bellow. According to the assumptions of incompressible, inviscid and irrotational flow, and using perturbation ...
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### Need help in quantitatively modeling solubility of carbon dioxide in beer.

I'm trying to model a 3D surface which reflects the solubility of $CO_2$ in beer. An empirically derived chart is available at this link. Solubility is empirically related to the pressure of $CO_2$ in ...
31 views

### Find Variants in list<list<int>>

Have a mathematic solution for this: I have some list<list> For example List{ List1 = {1,2,3} List2 = {4,5} List3={6} List(n) {k} } How can I find all ...
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### Discover where car is parked when car is using adjacent parking strategy to hide in N garages [duplicate]

The car can be parked in n garages lined up in a row. Each night the car is parked in some garage, and each day it is reparked to garages adjacent to the garage where the car was parked the previous ...
18 views

### Reference request: converting discrete models to continuous models

I have been reading a bunch of papers which take discrete models or agent-based models and convert them to continuous PDE models, using Continuum Mechanics, or such methods. Can anyone recommend a ...
37 views

### How to develop a continuous function for known pattern? [closed]

I am given a range of x and y and would like to develop a continuous function f(x). Meaning ...
28 views

### Positivity of solutions of an ODE system with non-negative initial condition [closed]

I have an ODE system that takes a mathematical model describing the dynamics between HCV and the immune system. My question is about the proof that the solution of the system is non-negative if the ...
1 vote
25 views

### Laguerre tessellations in real world

Aside from microstructures, where are Laguerre tessellations used in mathematical modelling?
1 vote
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### Geometric mean is to arthithmetic mean as arithmetic mean is to what?

I am interested in a type of "mean" $r$ associated to a set $\{a_1,a_2,\dots,a_n\}$ where $$e^r=\frac{1}{n}\sum\limits_{i=1}^n e^{a_i}.$$ I will call this the "? mean" for now ...
22 views

### Capacity planning and modelling

I have a business case in which I am going to model how many devices are required given the predicted workload in a series of monthly cohorts in the next ten years. The work could come from multiple ...
50 views

### Picking numbers from a list with Gaussian distribution (programming implementation)

If we have values: $x \in [0, 100]$ I would like to implement a method, where the bigger the value, the less likely it is that it will be picked. (something like a Gaussian curve, but with maximum at ...
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### Can someone help me solve this? Finding revenue function given two different prices and quantities

Have a Math for Econ intro course exam coming up and this question showed up in one of my past papers, I am afraid I do not know exactly what to do. Can anyone help me solve it? The following is the ...
38 views

### Can you modeling complicated dynamics without using differential/difference equations?

Let's imagine there is a phenomenon I want to understand. I have a few multivariate time series about the phenomenon but not a lot. I don't know how the variables are related to each other but from ...
75 views

### Rewriting system of second order differential equation as system of first order

Given a charged particle moving in an electromagnetic field. We have $N$ amount of point charges placed in $\mathbb{R}^2$ on the coordinates $p_i$. We also have a free particle moving in $\mathbb{R}^2$...
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### Conditional modelling of a binary variable based on the values of two continous variables

I want to model a binary variable $(b)$ from two continous variables $(x_{in},\:x_{out})$. These variables are $0\leq x_{in} \leq x_{max},\: 0\leq x_{out} \leq x_{max})$. I want the following three ...
1 vote
63 views

### Numerical solution of a Projectile motion problem

Lets consider the situation of a rocket launched from the ground onto some impact function $f(x)$. Assume that the impact function is just the $x$ axis, hence the projectile hit the ground at the same ...
21 views

### Is this SEIRD disease model a linear or non-linear least-squares fitting problem?

This is a system of ODEs I have set up to model a disease. I'm trying to fit the parameters for this model for a given data set using a least squares fitting algorithm. The parameters are the Greek ...