# Math.NET Numerics

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1. ## Implement Laplace transforms

convert laplace space functions to time domain and viceversa

1 vote
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2. ## Implement an extension method ".ToVector()" for convert a IEnumberable to a Vector

if it is possible, an extension method ".ToMatrix()" would be also helpful

thank you~

1 vote
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3. ## add Hypothesis-test function

1 vote
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4. ## Improving sparse matrix storage CRS by allowing the user to provide the sparsity structure of the matrix.

I'm new to math.net, but I've found some issues with the libraries.

One of these is related to sparsematrix and sparsecompressedrowstorage

I've also wrote a post within the discussion forum, but I've recieved no response.

The problem is simple: I've tried desperately to find a way to assign directly the sparse matrix in CRS format, but I've failed.
It seems that the CSR must be constructed starting from an already existing matrix. This would imply a big performace issue and memory allocation problems.
For istance, if one want to write a program to solve some physical problem with finite element…

1 vote
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5. ## Fix splines so that they can handle general lines

When adding the points of a circle ( Cos(t), sin(t) ) for t the values [0,6.28], I get complete garbage out.
It seems that the splines are unable to handle ambiguous values for y for a given x.
Splines should have a independent variable t, on which x and y depend. It seems this implementation has a t that somehow is coupled to x.
Interpolate should for example return a point, and the differentiate should return a vector for a given point.

1 vote
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6. ## Multidimensional Arrays Support

Support multidimensional array and tensors with higher than 2D (i.e. Matrix). This would open Math.Net to more users who need this functionality daily.

3 votes
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7. ## Dense and sparse matrix slicing based on input user defined indices

This should allow functionality similar to MATLAB:
Suppose that A is the following matrix

A = [ 10 20 30 40 ;
11 21 31 41;
12 22 32 42;
13 23 33 43]

and I = { 1, 2, 4 } and J = { 3, 4 }

A_IJ = A[I, J]

should return a slice of the matrix according to the indices specified:
A_IJ = [ 30 40;
31 41;
33 43 ]

The same idea is very useful for arrays and it should work in both directions, for example:

A[I, J] += some_3by2_matrix;

The same for sparse…

1 vote
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8. ## Add trigonometrical functions for degrees

For most cases it can be overcome with multiplying pi/180 and using loops, but it would make code simpler. Coming from Octave/Matlab it is something I am used to have

2 votes
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9. ## Quasi Random Number Generation

Otherwise known as low discrepancy sequences:
https://en.m.wikipedia.org/wiki/Low-discrepancy_sequence

1 vote
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10. ## Geometric Problems - Like Adjacent Points

Where's the namespace for geometric problems?

2 votes
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11. ## Implement the Studentized range distribution

https://en.wikipedia.org/wiki/Studentized_range_distribution

This distribution is used in the Tukey test for post hoc analysis of an ANOVA test.

6 votes
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12. ## support infinite precision

I really love the infinite precision feature of Google's Android Calculator. If you enter a number like π, e, φ, √2, √3, √5, etc., you can scroll to the right to get an infinite number of digits.

Such calculations should be supported by Math.NET Numerics, where results can get queried to get more (decimal) digits. Something like an IEnumerable<DecimalDigit> interface.

4 votes
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13. ## Implement finding extrema for cubic splines

I wanted to find extrema for a spline and had to implement it by myself, using the CubicSpline.cs of MathNet.Numerics. Unfortunately the Class is constructes thus, that I could not access the spline parameters which would have allowed my to simply write an extension method.

I propose the following addition to the class "CubicSpline":

public enum eExtremePointType
{
Minimum, Maximum
}

public class cExtremePointResult
{
public eExtremePointType Type { get; private set; }
public double x { get; private set; }
public double y [get;private set;}

public cExtremePointResult(double in_x, double in_y, eExtremePointType in_type)
{
x=in_x;
y=in_y;
Type=in_type;
}
}

///…

3 votes
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14. ## Eiganvalues and Eiganvectors

A function that can evaluate a square matrix for eiganvalues and eiganvectors similar to MATLAB's eig() function.

1 vote
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15. ## Implement Selected MATLAB Core Functionality

Implement a new class which is intended to provide syntax matched core MATLAB functionalities, such as flip(), linspace(), etc. I know linspace() and logspace() are already present with reordered inputs, but matching MATLAB syntax would prevent a lot of rewriting. Some of these could simply be wrappers for existing Math.NET functions, just so syntax matches.

Validation of this functionality would be such that inputs/outputs match the MATLAB implementation. Simple functions at the start, and more complex ones as time goes on.

3 votes
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16. ## Valuation of top eigenvalues/eigenvectors only

Hi,

CPU time to perform Matrix diagonalization scales like n^3 where n is the size of the matrix. In many applications, however, one needs to know the top eigenvalues/eigenvectors only.
MKL provides this: "LAPACKE_dsyevr" where one can select how many eigenvalues one wants to compute.
Would be great if this functionality was available in mathnet!

1 vote
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17. ## Add Matrix indexing using int arrays for row and columns indices to give sub matrix

Allow the following A[row, cols] where each of rows and cols are int arrays.

1 vote
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18. ## implement a machine learning library

For modern datascience we need machine learning. Hence for .NET a modern machine learning library would be very welcome, especially one with a good F# interface. It should contain the most used standard algorithms & models like

- clustering: k-means, spectral clustering, kernel k-means, gaussian mixture, ...
- classification & regression: (regularized) generalized linear models , neural networks (classic & deep learning), kernel models (SVM, kernel logistic regression,...), probabilistic (max likelihood) & Bayesian methods/graphical models/gaussian processes, decision trees & random forests,...
- ensemble methods (bagging, boosting,...)
- dim reduction (SVD, kernel SVD, manifold learning, sparse representations (L1 regularization),...)
- probabilistic…

54 votes
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19. ## Implement SetSubMatrix(int[] rowIndices, int[] columnIndices, Matrix<T> subMatrix)

Implement method:

Matrix<T>.SetSubMatrix(int[] rowIndices, int[] columnIndices, Matrix<T> subMatrix)

where

int[] rowIndices
The row indices to copy to.

int[] columnIndices
The column indices to copy to.

Matrix<T> subMatrix
The sub-matrix to copy from.

This would enable us to set a larger number of entries at the same time.

1 vote
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20. ## Implement Skew Normal distribution

4 votes
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