# All Questions

2k views

### Levels: how do they work?

I cannot understand how Mathematica manages levels, and so it's always a painful try-and-fail to use Flatten. Can someone please give me a very clear definition? ...
48 views

### Diff eqs can be solved?

I'm trying to solve a pair of coupled differential equations, but am having trouble making DSolve evaluate my equations. ...
70 views

### Filtering of an unwanted frequency through a Fourier Transform

I have a data set with evenly spaced data points. The plot is frequency vs. intensity. The overall shape of the plot is an upwards curve into a plateau, this cannot be seen in the data as this is an ...
35 views

### Mathematica's steps towards the result of a definite integral

I am interested in this definite integral: \eqalign{\int_0^\infty {x^2 \log(1-e^{-x})}\; dx\cr } That is: ...
46 views

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### How to write a function that returns the combined output of several built-in functions

I am trying to make a module that takes a Boolean function, and prints the following: the function's truth table the function's NOR epxression the function's minimal Disjunctive normal form So far ...
8 views

### Manipulate - 3 sliders for a list of 3 elements

I'm trying to create a slider for a list of 3 elements. I know that I can create a 2D slider for a list of 2 elements and it's impossible to create a 3D slider for a list of 3 elements. So, I just ...
10 views

### FindDistributionParameters fails to find a mixture of user defined sinh-arcsinh distributions

I have some data (1593 values). I first binned it using the Knuth rule and fitted a function that is a linear combination of two sinh-arcsinh functions. I then ...
13 views

### How to hide and show graphics within Show[] function (in Manipulate wrapper)

There is a well documented way to "Dynamically Hide and Show Plots" (link). In the example 'Opacity' option is effectively used. Is there an efficient way to make the same functionality with "Show"? I ...
101 views

### Does Mathematica have an equivalent of C's nextafter?

In C (and many other programming languages), there is a function double nextafter(double x, double y) which takes two (IEEE 754) floating-point numbers and ...
436 views
+50

### Import an SPSS, SAS, or STATA file into Mathematica

I would like to import the World Value Survey data file into Mathematica, but it's only given in spss, sas or stata formats, which are statistical analysis softwares format I think. I can't get to ...
47 views

### nonlinear differential equation

For such a equation $$-y''(x) + x^2\cdot y(x) - |y(x)|^2\cdot y(x) = 0$$ with initial conditions: $y(-500) = 0$ and $y(500) = 0$. I write in mathematica ...
44 views

### Map with multiple arguments

I have a function f[m,n] and a list of arguments args = {{m1,n1},{m2,n2},{m3,n3},{m4,n4}, ...} that I want to apply to it. I ...
39 views

### Eigenvalues of the nonlinear Schrödinger equation

As an exercise I have to deal with a nonlinear time independent Schrodinger equation eigenvalues and eigenfunction, ...
80 views

### Swing of the pendulum [duplicate]

I would like to visualize a swing of the pendulum. I want to write a function springmass[z, nzigzag], which will draw the spring (line) and the swinging weight ...
24 views

### Goldbach Conjecture …Every even integer > 2 is the sum of two prime numbers.Find a program in mathematica to solve this problem [on hold]

Every even integer > 2 is the sum of two prime numbers and Each odd integer > 5 is the sum of three prime numbers USING THE SIEVE OF ERATOSTHENES....
55 views

### NIntegrate and Sum give different results in summing functions [on hold]

I am using these two functions: ...
23 views

### ANOVA test on dataset

I have a dataset with 3 groups and two variables. I want to do ANOVA test on the three groups for each variable. Does anyone know how to do this? ...
273 views

### Drop selection of columns from a ragged array

I have an application where I need to drop some arbitrary list of columns from a ragged array (where of course the shortest array rows have at least all the specified columns). E.g., given a ragged ...
127 views

### Parametrize a circle as a tube?

I have this code: ...
14 views

### Recurrent equations [duplicate]

I want to make a relation to show the first 7 elements that don't have the number 7 in it. So far i know how to make it to show the first 7 elements with RecurrenceTable[{a[n + 1] == 7 a[n] + a[n], ...
153 views

### Build an InterpolatingFunction with ElementMeshInterpolation

Suppose you have a function f[t_, x_, y_] := t (1 - x^2 - y^2) defined for {x,y} in ...
109 views

### Expressions containing globally undefined symbols inside a function where they are defined

Consider the following code. f[a_,b_]:=x; Clear[a,b]; x=a+b; f[1,2] It returns a+b. However, from a certain viewpoint, one ...
786 views

### How do you set attributes on SubValues?

SubValues, as discussed in a previous question, are declared as follows ...
326 views

### How to write a function-defining function which stores the function arguments in a stack?

I have a function-defining function SetAttributes[DefFn, HoldAll]; DefFn[f_[args___], body_] := f[args] := body; I am trying to modify this function to record ...
59 views

### Evaluate recursive funtion as a whole before computing a recursive step

I'll try to make a basic example of my problem with $n$ being an array of elements, ex. $\{1,2,2,3,3,3\}$: If i have a sum which needs a computed value i would like to compute it beforehand and store ...
67 views

### Undo history cleared after removing comments - bug?

If I've written some code followed by a comment, like this: x(*y*) and I remove the comment by first removing the right delimiter and then the left, my undo ...
73 views

### Creating truth tables

Hello guys i need help about this problems: I should write module in mathematica which receive function f. Module should write on screen: -Truth table of function f -Boolean expression which contains ...
365 views

### How can I generate and randomly assign color to annular sectors?

How can I generate such an image and fill every annular sector with a random colour?
87 views

### How can I make FilledCurve smoother?

In How can I generate and randomly assign color to annular sectors? J.M. showed an interesting way to create a sector graphic using FilledCurve. Unfortunately it ...
54 views

Consider: ...
19 views

### GraphicsRow - vertical axis ratio [on hold]

I have following code: ...
134 views

### How to write my own interpolation method

I was comparing results of spline interpolation in Mathematica and C++/gsl-library Results of interpolation are different if I use ...
180 views

### Does Mathematica have an equivalent of Python's float.as_integer_ratio?

The Python programming language has a float.as_integer_ratio(x) function which exactly converts an IEEE 754 floating-point number into a numerator/denominator pair ...
365 views

### No response to an infinite limit

Trying to compute this limit, things seem to get frozen, even for hours. What would you recommend to fastly compute it? ...
168 views

### Evaluating Erf[x] in arbitrary precision

Is it possible to evaluate Erf[200] with arbitrary precision? I only get 1. as result but I would like to know if a arbitrary ...
169 views

### What is the best way to write a polynomial in the Bernstein basis?

The Bernstein basis of polynomials of degree $n$ is the set of polynomials of the form $$\binom{n}{k} t^{n-k}(1-t)^k$$ where $0 \leq k \leq n$. What is the best way to transform a given polynomial ...
19 views

### physics - swing of the pendulum [duplicate]

I should visualize a swing of the pendulum. I should write a function springmass[z, nzigzag], which visualize the spring (line) and the swinging weight (rectangle) ...
86 views

### How can I make a pretzel shape using bezier curves?

I am trying to make a pretzel shape,but I cannot seem to get the loops even. Eventually, I need to make the pretzel shape loop in 3D so I need to nail the 2D concept first. Here's what I have so far. ...
43 views

### Forcing a locator button to remain on the surface of a sphere

This question may or may not be possible and might be a hard one to answer. Suppose that I have a sphere centered at the point (1,2,-1) with radius 3. Is it possible to place a locator button on the ...
381 views

### Arbitrary precision spline interpolation

Current implementation of Interpolation does not allow arbitrary precision spline interpolation. Yu-Sung Chang say here that "it is not hard to implement it ...
514 views

### Is there any fast way to solve a quadratic matrix equation in Mathematica approximately?

Let the square nonsingular matrix $M$ is a given convergent matrix. What are the best scalar values for $\alpha$ and $\beta$ (in the real numbers domain), at which the following quadratic matrix ...
60 views

### Changing from Dashed to Solid

I have: Graphics[{ Blue, Thick, Arrow[{{0, 0}, f1}], Arrow[{{0, 0}, f2}], Red, Arrow[{{0, 0}, f1 + f2}], Dashed, Blue, Line[{{-9, 0}, {12, 0}}] }] ...
281 views

### What algorithm does Plot use to determine abscissas?

(I'm hoping this question is not hopelessly naive...) My understanding is that Plot's strategy is to generate a list of abscissas, evaluate the argument expression ...
212 views
+50

### Transform an expression to remove the singularity

I have the expression Sin[c x]/c. Clearly it is undefined at $c=0$, but that is merely a removable singularity, since \frac{\sin(cx)}c=x\frac{\sin(cx)}{cx}= ...
136 views

I'm trying to replicate the figure below. Now a nice first approach to do this is by using Mathematica, by making some kind of contourplot with circles and just add a gradient to the contourstyle. Now ...
138 views

### Regime Change Stochastic Process

I would like to simulate an Ito process in which the drift and diffusion terms change after hitting a boundary for the first time. For example, a Geometric Brownian Motion X which has 0 drift and ...
33 views

### How to reduce trigonometric expressions under special conditions

For the following problems I used "FullSimplify" and "TrigReduce" but I manage to reduce more ...