# All Questions

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### Problem with curve fit using integral

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 ...
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### Construct a master curve from data

I will try to be as informative as possible. Clear["Global*"] I have the following data ...
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### Fast 1D BinCounts Alternative

I have lots of data which looks like this example: ...
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### I want RSA algorithm matlab code implimented on image [on hold]

I want RSA algorithm matlab code implimented on image encryption and decryption
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### How can I prove the following statements about matrices? [on hold]

Given A∊M_nxn show that the following statements are equivalent: (a) Rank(A)=n (b) det(A)≠ 0 (c) A has inverse (A^(-1)) Please, Help me :) thank you very much! :D
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### 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 ...
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### 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 ...
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### 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. ...
51 views

### Finding the limit of a complicated expression

I've never used Mathematica before, so I'm really struggling to use it right now. I have a complicated function ...
23 views

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

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

### Shading a region where an inequality is satisfied

I'm creating solution sets for a calculus course and need to shade the region in $\mathbb R^2$ such that $x^2 < y < x^4$. This is what I have so far: ...
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### 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 ...
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### Trace and SameTest in Union

This question is actually two question. First, I feel so stupid that I just don't understand the use of theSameTest option in ...
24 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?
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### 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: ...
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### Having a function check a column and perform a task every time an entry satisfies a condition

So I have a matrix (technically a table) points = Table[{x, f[x]}, {x, Range[0, 2, .1]}]; Which gives something like this in matrixform \begin{array}{cc} ...
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### 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.
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### Increase Performance in the Manipulate Command

The code below pretty much looks like and does what I want it to. However, it is sluggish. I realize I have many calculations, and perhaps this is the best I can hope for. But if anybody has any idea ...
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### Second Order ODE (Bessel Function) with a dependent variable in the BC

I have obtained an analytic solution to the following problem however I lack the knowledge to generate a numerical solution using mathematica. I'm reaching out to get an idea of what functions I may ...
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### Solve Always with Assumptions

How can I use the Solve Always function imposing some assumption on the parameter space of the symbolic variables? Thanks!
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### Plot a function with respect to two parameters that are not explicitly function parameters

$$function = |\delta|\frac{I_1(\kappa)}{I_0(\kappa)}$$ where $I_0(\kappa)$ and $I_1(\kappa)$ are the modified bessel functions of the first kind of order $0$ and $1$ I want to plot the function in ...
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### Plotting piecewise functions with distinct colors - issue found

I've been making use of the following thread: Plotting piecewise function with distinct colors in each section A handy feature I found there goes as follows: ...
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### SeriesCoefficient is not reading fractions consistently [on hold]

I am trying to use SeriesCoefficient to do the following calculation ...
32 views

### How to scale one axis of a 3D plot?

I would like to scale one of the axes in a Parametric3DPlot. I tried adapting the recipe given in this answer to this case, but, as shown below, this attempt ...
44 views

### Indexing a value within a table function

Is what I'm looking to do possible? I know that I can get it to work with a for loop, but a table would make things much neater. What I need to do while calculation the table below is to reset the ...
77 views

### Code for Newton's Method [on hold]

I'm trying to write a program for finding the root of f(x)=e^x+sin(x)-4 by Newton's Method but I'm instructed to not use the built in function and write the code from scratch. I'm pretty new to this ...
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### Reduce set of symbolic equations to linearly independent subset

Given a set of symbolic equations $f_i(x_1,x_2,...,x_n)=0$ in several variables, for example f1=x+y-z; f2=x-y+z; f3=3x-y+z; I would like to apply a function ...
77 views

### Innovators differential equations [on hold]

We have a question: Is there a channel that innovators can use to approach the makers of Mathematica (Wolfram Research Inc.), to present new discoveries? Mathematica was an essential tool in my own ...
33 views

### stop rule for Nonlinearfit and best fit

I want to understand the rule under which the function Nonlinearfit stops to give the final result. I know that if the number of iterations exceeds ...
61 views

### How to prevent a definition from overwriting my input

I developed the following manipulate code to be a limited knockoff of Polking's dfield. I export the code to Enterprise CDF so that one may type a first-order ODE into the input box and create a slope ...
52 views

### Plot column using some list as x values? [on hold]

I've got a mathematica notebook that uses RK4 to successively approximate solutions to a vector valued DE. The output is a nested list similar to: ...
86 views

### Speeding Up RandomVariate

Consider the following code where we first take 1000 independent samples from a Poisson distribution, and then take 1000 independent samples from 1000 different Poisson distributions: ...
61 views

### Please, help to find the area enclosed by the curves: ContourPlot[{x + y^2 == 0, x + 3 y^2 - 2 == 0}, {x, -2, 2}, {y, -2, 2}]

Please, Help to find the area between two curves. ContourPlot[{x + y^2 == 0, x + 3 y^2 - 2 == 0}, {x, -2, 2}, {y, -2, 2}]
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### System cannot be solved with methods available

I'm trying to solve the following equation, but the command Solve hasn't been successful so far. Any ideas? ...
45 views

### Import all tweets with specific hashtag

I want to analyze twitter data connected to a specific hashtag (#bokmässan2013). As I understand it, Twitter has recently made their complete archive of Tweets retrievable by means of API. How can I ...
27 views

### Does NDSolve automatically simplify the system of equations for Hermitian matices?

I am currently starting to solve numerically a system of differential equations like this: $\dot{A}(t)=S(A)A(t)$ Here, the matrices are of dimension $d\times d$. $S(A)$ is some superoperator that ...
34 views

### Arrays with two different types of indices

Is there a way of having arrays which have, so to speak, two different depths $m,n$? From the point of view of memory usage, it would be the same as an array of depth $m+n$, but I would like to ...
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### How can I plot the normalized distribution of the Riemann zeta zeros?

Given a list of eigenvalues or a list of Riemann zeta zeros, how can I plot this famous plot found here: On the page referred to, You need to click on "Programs", "The Riemann zeta function" and ...
39 views

### Put results of a loop in a table [on hold]

I have a loop that gives me a number with each iterator. I want to place in a table, the number and the value of the iterator, for example: Table[{i1, number1},{i2, number2}...]. How can I do ...
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### speeding up Solve(ing) the Diophantine equation

Trying to solve the Diophantine equation (or variation?) using Solve in order to generate some chemical formulas. I need to generate all possible solutions. The ...
184 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: ...
63 views

### Partitioned matrix operations

I have a $(2 \times 2)$ matrix whose elements are themselves $(2 \times 2)$ matrices (i.e., a partitioned matrix), e.g:  M = \begin{pmatrix} A & B \\ C & D \end{pmatrix}, \quad \quad ...
149 views

### Strange behavior in ContourPlot?

I'm have a Abel's differential equation: ...
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### Number triangle programming challenge, separate columns

I am about to enter this number triangle https://oeis.org/draft/A262964 in the oeis, but I don't know how to program it properly. This is partly a mathematics question so I could ask it at math se ...