# Questions tagged [mathematica]

Mathematica is a software package for symbolic mathematical computations.

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• 335
1 vote
3k views

### On what basis we are evaluating variance is high or low? [closed]

I am having a below case where N = 300 , Mean = 67 and SD = 30. With the above data we can say the variance is high because of SD = 30. My question is how we are defining it as high on what basis we ...
• 111
1 vote
495 views

### Unkown 6-sided dice. After 600 rolls frequency for all sides exactly equal. What is the chance, that rolling "6" with this dice has frequency > 1/6?

Although it is unknown dice, the symmetry of the evidence tells us, that we can treat the dice as fair, so the chance should be exactly 50%. But if we simulate it by hand, the result is less then 50%:...
• 2,200
1 vote
1k views

### Normalizing error variance scale

Imagine we have two sets of data m1 and m2. m1 components have the dimension of [m^2/s] and m2 components are measured in [cm^2/s]. e.g. ...
• 505
1 vote
98 views

### How to simplify the understanding behind Hypothesis Testing? [duplicate]

Quote recently, I have trying to understand this confusing idea of Hypothesis testing. Although I am pretty much clear with the way it works, that is: Choosing a test statistic Then choosing a Null ...
• 11
1 vote
84 views

### What mathematical background do I need to do research in field of deep learning

I am familiar with few deep learning models and I understand how (little bit why) CNN/RNN works. But I still cannot make sense of new research papers. I want to dive deeper into field of deep learning ...
1 vote
130 views

### Is there any relationship between two normalized gamma distributions?

Consider two normalized gamma distribution functions $\frac{\Gamma(x,y)}{\Gamma(x)}$ and $\frac{\Gamma(nx,ny)}{\Gamma(nx)}$ where $n$ is a positive integer value. Is there any relationship between the ...
• 11
1 vote
101 views

### How can I incrementally calculate the 4 central moments in statistics (mean, standard deviation, skewness and curtosis) when a value is removed?

I'm incrementally calculating the 4 central moments. When a value x is added and n, M1, M2, M3 and M4 are some predefined values, I'm using the following algorithm: ...
1 vote
401 views

### Deriving parameters of an extreme value distribution from an initial distribution for finite n

Background: For my research I've been trying to model brittle fracture mathematically. The basic concept is that a brittle materials fail because already existing small defects such as small cracks ...
• 13
1 vote
51 views

### Measuring Autocorrelation in Tail Events

I have a single time series of financial data (stock index returns) and would like to study the autocorrelation among (log-)returns that are classified as "extreme", for example via exceedance of a ...
• 111
1 vote
35 views

### Visualising n vectors of length n in a periodic fashion

I'm currently working on a specific problem in a periodic structure, for which I obtain a set of eigenvectors that I would like to plot. It is probably easiest if I give you an explicit example, then ...
• 211
1 vote
911 views

### Problem with multivariate lognormal distribution in R [closed]

I'm using the R package compositions for the multivariate lognormal distribution. This is the only package I found that supports it. However I'm not sure how this ...
• 1,771
173 views

### mathematical proof that if the vectors 𝑞⃗ and 𝑑𝑖 all are normalized unit vectors [closed]

In a vector space model when we are given a query as a vector 𝑞⃗ and documents 𝑑1 , 𝑑2 …, we usually rank the documents in relevance to the query vector using cosine similarity. Show by a ...
2k views

### How to read/visualise this confusion matrix?

I was offered a confusion matrix, which is called Parametrised 5x5 confusion matrix by authors where I extracted the values and where the diagonal has the correct results (0 in all); the results are ...
359 views

### How to estimate storage needs using the PERT distribution for filesizes? How to aggregate them without falling into the flaw of extremes?

Lets say I know that I am going to store the information of 10,000 people each year for 4 years, that is 40,000 files. Now If I estimate that on the best case scenario the information from each ...
• 301
865 views

### Neural Network - Classification from Time series

I'm a .Net programmer who is fairly new to neural networks, but I know some of the concepts. I have connected .Net to my copy of Mathematica 10 This is a classification Our business problem is ...
• 103
Let $a \sim\mathcal{N}(6.532056,0.06532056)$,$b \sim\mathcal{N}(8.390961,0.08390961)$ and $c \sim\mathcal{N}(8.736566,0.08736566)$. We use $\mathcal{N}(\mu,\sigma^2)$ notation unless specified ...