# Tagged Questions

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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### Mathematical calculation

I encountered during my reading to ridge regression that $$(X^TX+\lambda I)^{-1}X^TX = I-\lambda(X^TX+\lambda I)^{-1}$$ What mathematical manipulation has been done here? Thanks in advance
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### Proportionally Distributing $N$ items across $B$ bins.

My question is similar to this: Proportional Distribution My problem follows: I have $N$ items that cannot be broken up into fractional components, but should be distributed across $B$ bins where ...
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### Why is there a division by $z$ in this mathematical model of a camera?

I'm reading the OpenCV documentation on what mathematical model they use for a camera. The below quoted text can be found on this website, scrolling down to the section "Detailed Description". I do ...
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### Multi Valued Model

Suppose we have a set of observations $\{(x_1,y_1),...,(x_n,y_n)\}$ and a function $f$ that provides an optimal (in some sense) prediction of an output given an input. Also suppose that for some $i$ ...
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### Can anyone answer this equation or tell me what it is? [closed]

I have been sent an image, and have no idea what it means. Think this is the best site to try. The image is of the equation $$W_T=\sum_{i=1}^nW_i\;.$$
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### Which of the following is more efficient?

In an auditorium where 100 people are sitting, with 10 people in each of the 10 rows. What will be the most efficient way of increasing the distance between the first row and the stage: by making the ...
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### asymmetrical sine wave

How do you model a sine wave that begins to shift over asymmetrically (like a ocean swell approaching a beach)? Is sine even the right function for this model, or is some other type of function better?...
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### Match harmonics while decoding the speech signal

There is a matlab's program. In the input parameters is a wav file. After executing a program there are appearing an array of frames. Frames partially recover each other. In each frame there are ...
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### function to model breaking wave

What is a good parametric function to model a breaking wave (im ok with something complicated)? More specifically, I am looking for a general form, such that it looks like a normal swell and then as a ...
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### Modeling population density with PDE

If we know that the population density $u(x,t)$ in some lake varies as a function of $x>0$ and time $t$, where $x$ increases downwards with depth, and that the population diffuses with constant $D$ ...
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### Conditioning Poisson on Poisson [closed]

There is a bus, whose departure at a stop is distributed as poisson(mu). People arriving to the same stop is distributed as poisson(lambda). Find the PMF of the number, N, of people on any given bus. ...
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### Model for spread of infection, with vaccination

I'm trying to solve following problem: $N = 10^6$ ... number of people $ir = 8\%$ ... infection rate time unit - 1 day And when there are 3% of population infected, vaccination begins. Its effect ...
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### Using a continuous function to describe discrete data

I've always been told to use discrete functions with discrete data and continuous functions with continuous data. This especially comes to light when talking stats and people emphasize the difference ...
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### Modeling simple linear equations

This should be pretty simple but I'm blanking on this. I need to model (graph) how path 1 becomes equally as efficient as path 2 as the distance of path 2 increases. distance of path 1 (from A to B) =...
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### how do I resolve equations that are both dependant on each other

I'm working on a project concerning the ideal power equation of aerodynamic bodies seen here: $$P = \frac{1}{2}C A D v^3 + \frac{W^2}{Db^2v}$$ where $P$ = power, $C$ = coefficient of drag, $A$ = ...
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### How can I adduce the mathematical model in my master thesis?

Please explain how to adduce and describe the mathematical model obtained by neural network modeling, if the model contains 50 inputs and five neurons in the hidden layer. How to show values of ...