# All Questions

82 views

### RandomVariate of a custom distribution gives only negative points

I don't understand why the following code ...
206 views

### Why Drop and Take do not support a operator form

Since Mathematica 10 introduced the operator form, I have been a big fan of it. Whenever I use some buit-in functions, I first look up whether they support operator form. To me, it was quite ...
49 views

### How to get coordinate from spline interpolation

Hi, I would like to find 10 coordinates between each points of this spline interpolation. I have done some research, but cannot find an appropriate answer. Any help will be appreciated. ...
2k views

### Find intersection of pairs of straight lines

I have a list of 24 points, in which two consecutive points (1st and 2nd, 3rd and 4th, …) are supposed to form a line: ...
84 views

### Simple arithmetic with Irrationals fails

While solving a simple puzzle that asked for a few calculations in plane geometry, I ended up with this expression: $-\frac{55}{2}+\frac{\sqrt{27233}}{2}+\frac{1}{2}(55-\sqrt{27233})$ Or, in ...
78 views

### RegionPlot looks wrong

I have the following simple RegionPlot of a RegionUnion: ...
103 views

### RegionPlot with Assumptions

I am trying to evaluate the properties of a multivariate function $f(a,b,x,y)$ with respect to $x$ and $y$ given assumptions for $a$ and $b$. An example without $a$ and $b$. ...
36 views

### How to write a function using SeriesCoefficient?

The $k$-th complete symmetric function $h[k,X]$ is a function of any set $X = \{ x_1,x_2, \ldots \}$ given by the coefficient of $z_k$ in the geometric series expansion of $\Pi_i \frac{1}{1-x_i z}$ . ...
82 views

### Symbolic Integration gives wrong answer [closed]

I have tried to integrate the following expression in Mathematica 10.1 ...
79 views

### Express function derivative in terms of the function itself

I'm working on a minimization problem that involves the standard logistic function $f(x) = \frac{1}{1+e^{-x}}$ along with its simple derivative $f'(x) = f(x) \cdot (1 - f(x))$ The correctness of ...
46 views

### Troubles importing date and time from CSV file

I'm trying to import CSV file with the following format: 20150803 00:00:01.649,1.09675,1.09678 using this code: ...
63 views

### Eigenvalues FEAST method - performance is very variable

I am running the FEAST method option for Eigenvalues on sparse matrices of dimension around 500,000. I look for about 50 ...
76 views

### Fourier of List

I have such a problem. I try to evaluate and plot the spectrum of large list, and this is what I get: ...
49 views

### Formula lookup wildcards [closed]

When I give the command: FormulaLookup["sphere"] I get no results even though I know there are formulas involving spheres. Do I need to use some kind of wild ...
105 views

### How to plot zeros of confluent hypergeometric function

I am fairly new to mathematica so I need a little bit of help. I need to plot the zeros of an equation containing confluent hypergeometric functions. The equation i need to solve is given by the ...
62 views

### What is the Java converter?

I notice that there is a directory: C:\Program Files\Wolfram Research\Mathematica\10.2\SystemFiles\Converters\Java. What is this? I could not find any documentation ...
3 views

### How can I solve this derivative (Differentiation under integral sign) [migrated]

How can I solve this integral? d/dy( integral_1^pi (sin(x y))/x dx) (I dont know how to type equations here so here is a screen-shot)
63 views

### Fast 1D BinCounts Alternative

I have lots of data which looks like this example: ...
32 views

### Problem with curve fit using integral [on hold]

I need fitting a Langevin function on a experimental data, but one parameter must be firstly optimized by using a Lognormal distribution. The complete expression could be written as: The integrate ...
38 views

### How to reorder and combine terms in a polynomial with multi-variables?

I have a polynomial with the coefficients of {a1, b1, b2} ...
29 views

### I want RSA algorithm matlab code implimented on image [on hold]

I want RSA algorithm matlab code implimented on image encryption and decryption
587 views

31 views

### How effect is the mathematica automatic machine learning function like Classify? [duplicate]

The documentation said use Classify, you will get state of the art machine learning result. But since the Classify function of ...
29 views

### How to know the internal pre-processing of automatic machine learning function Classify?

In the Highly automatic machine learning page, it is said the function like Classify and Predict will do things like automatic ...
27 views

### Is it possible to programmatically close a CDF? [on hold]

I've created a number of CDF's that I have parked in dropbox for my students. On each these CDF's is toolbar with a dropdown menu that opens up another cdf from the dropbox. It works great. ...
74 views

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### Unpacking NumberForm expressions

Given a NumberForm expression, e.g.: NumberForm[N[Pi], 10] How does one get the underlying numerical expression (short of ...
102 views

### NDSolve Poisson PDE for rectangle with hole

When I solved the Poisson PDE with function NDSolve in a rectangular domain with hole in the center, and search the first derivative with x and y why appear these protrusions on the diagram around the ...
37 views

### Simplify square root term by taking variable inside root

I want to simplify expression $\frac{\sqrt{1+b+b^2}}{b}$ to$\sqrt{1+\frac{1}{b^2}+\frac{1}{b}}$. How to achieve this?
46 views

89 views

### How to solve heat equation with Robin type conditions with NDSolve?

Could you help me please to solve following problem! I need to solve one-dimensional heat equation with Robin type boundary conditions. But Mathematica find only constant solution with no dependence ...
38 views

### decomposing an expression into absolutely positive terms

I have a big ugly expression which, for unimportant (here) reasons, must be greater than or equal to zero. It is formed from terms which themselves are greater than or equal to zero. As such it ...
240 views

### Partial Differential Equation in Parallel

is there any native way to implement multi-core parallel solving of PDE in Wolfram Mathematica? WM 10 now supports Finite Elements Method, but it is actually useless without parallelization. Usually ...
96 views

### Differentiate a numerically defined function

My function is f[a_, b_] := NIntegrate[Sqrt[(Cos[t] - a)^2 + b^2], {t, 0, Pi}] I want to calculate g[1,1] where ...
68 views

### Merge two matrices where one may be empty

In a loop, I want to merge two matrices A and B where B is sometime empty. Example: ...
39 views

### Help me solve this equation; I believe this is a transcendental equation [duplicate]

please can someone help me solve (x*L)+B*tan(x*L)=0, solve for x when B=10;L=0.1. The equation looks innocent but I need to find 1st 5 roots of equ.
144 views

### How do I rotate a curve?

I have a circular segment defined as: ParametricPlot[5 {Sin[ϕ], 1 - Cos[ϕ]}, {ϕ, -0.2, 0.8}, PlotRange -> All] which I have to rotate around point ...
196 views

### How to compile self-referencing functions (to perform recursive a task)

How do I compile a self-referencing function to perform iterative tasks? The naive approach doesn't seem to work. Here is a simple example to illustrate the problem: ...
242 views

### What is a good way to display many discrete probability distributions on the same plot in Mathematica?

For something like 2 to 30 distributions each with 2 to 30 values. If we assume the distributions have unique values, a standard stacked bar chart is insufficient, but maybe something similar would ...