# All Questions

120 views

### Algorithm in RandomChoice[{w1,w2,…}->{e1,e2,…},n]?

I wonder if someone happens to know the actual algorithm implemented in the particular overload of RandomChoice that handles explicitly presented discrete ...
205 views

### Plotting solutions of differential equations with different parameters [duplicate]

I want to plot x[t], when i manipulate w from 0.1 to 1.5. Here is what I've attempted, which does not work as expected. ...
72 views

### How to solve an inequality

I am trying to solve the following inequality: Assuming[{R[k] >= 0, R[k + 1] = R[k] - 2^N Y, Y >= 0 && N >= 0}, Refine[Re[R[k + 1] >= 0]] I ...
181 views

### Skewness of distribution vs. skewness of distribution's PDF

I'm having trouble understanding why the skewness of built-in distributions is not the same as the skewness of their probability density functions. For example, the following are different (the first ...
99 views

### Plot graphs in different colors

I am generating a set of plots and exploring how changing a parameter affects the plot shape. I want each plot to be a different color, but the color rule i'm applying seems to only work for the last ...
107 views

### I'm trying to filter a date range by day of month and day of week - what am I doing wrong?

I am trying to generate a list of dates that match two criteria: they have to all be the first of the month, and they have to be a particular day of the week, Sunday in my case. The code I have ...
294 views

### intersection between function and plane

I try to solve a ODE system of equations and i want to plot the intersection of the 3D solutions with a costant plane. To do this i use the follow code: ...
53 views

### NSolve or Reduce for obtaining the results and connecting roots

Here I have one problem how to solve numerically equation for different values of one parameter x. I used just two digits because of length, but for x=0.57 I should have one real root and for others ...
214 views

### Why does Plot[Hold[x], {x,0,1}] work?

It appears that, counter to my expectation, all of these (and probably many others) seem to work fine: ...
289 views

### Converting from TableForm to Grid

I wonder if there is an easy way to convert from TableForm to Grid. I have an existing data format that uses the Table function that I’d like to prettify…. Let’s setup a nested table as follows: ...
71 views

### Assign a value to a variable without using Set or SetDelayed?

I supose probably yes, but at the end I assume that internally mathematica has to use Set or SetDelayed. Am I right? Background: I am developing a super simple phraser that takes a code description ...
137 views

### Boundary Condition Problem with Green's Function

My temperature distribution looks like: Mean wire temperature is : To[x_] := 2 c1 Cosh[x a1] + a2 And it is continuous at two points. In positive part: ...
104 views

### How is Wolfram Language different than regular Mathematica? [duplicate]

From all I can see there seems to be no difference between "Wolfram Language" and regular Mathematica. Is Wolfram just a marketing rebranding of Mathematica or is there a new capability I am missing?
140 views

### Import YAML file into Mathematica

Has anyone implemented the import of YAML data files into Mathematica? I suppose some sort of transformation into a nested list of rules would be the way to do it. Thanks
179 views

### Plotting a list in real time

I would like to use Mathematica for a presentation and have a list plotted in front of my audience, one coordinate at a time. How would I go about plotting a list progressively in real-time, ie the ...
482 views

### Categorical Distribution

Suppose I want to do calculations with a random variable $X$ that has a simple categorical distribution (a.k.a generalised Bernoulli distribution or discrete distribution). I was expecting to be able ...
102 views

### Merging two held expressions into a held compound expression

Consider e1 = Hold[a = x + x; b = y + y + y]; e2 = Hold[c = a + a + b + b + b; c^2]; How can I obtain the following? ...
160 views

### Order of symbols in Graphics labels

Do you have any idea how to force an order of Greek letter in the graphics? When I type in AxesLabel -> {Cost, Δ OverBar[π]} the order is π Δ. How can I ...
615 views

### Why Mathematica can't solve this? NSolve or Solve

I want solution of x and y which should be positive real numbers ...
491 views

### 2d heat conduction equation: Boundary and initial conditions are inconsistent

I have the following code for a 2d heat c equation: ...
92 views

### Define inverse for the custom operator

I want to define simple matrix algebra (inspired by the following posts: Block Matrix Algebra with Mathematica ; How to define custom operators ). I assume the funtion ...
222 views

### GatherBy and two conditions

I have a list of 4 dim points, given by ...
229 views

### For loop in Mathematica

I have set of statements ...
65 views

### Solve equation with two different sets of replacement rules

I want to solve eqn for c0. I want to do it with both replacement rules. I realize I could just use solve twice, once for subsCoke, and once for subsPepsi. I'm trying to do it in just one Sovle to ...
68 views

### Problems with manipulating plot in a dialog

G'day, guys. Here is a silly problem I am struggling with. ...
141 views

I tried this ...
233 views

### Shooting method for solving 3rd Oder ODE with RK method

This is my 3rd Order IVP. D[y[x], {x, 3}] == (m/2)*((D[y[x], x])^2 - 1) - ((m + 1)/2)* y*(D[y[x], {x, 2}])^2. Initial conditions given are as follows ...
422 views

### Find an equations of motion using Euler Eqution [closed]

I am a completely new to Mathematica, so my question and code may look silly. I need to find a equation of motion of a point particle of mass m moving in a potential V(x) = A abs[x]^n. (n=1,2,3,4,5,6. ...
518 views

### Why is my solution to PE #5 so slow

I'm new to Mathematica and it was suggested to me to go through the Project Euler problems in order to learn it. However, I can't quite figure out why my solution to #5 is so slow. The problem: ...
227 views

### Why can't Mathematica solve this system of equations?

I am trying to solve the following system of equations for three unknowns Theta, Nu, and K. All the other parameters are constants. The third argument in Solve, ...
117 views

### BlockRandom and NestList: how get random maps with the same noise?

I need to compare solutions in random systems with the same noise and different initial conditions. Here I run twice a random map with the same initial condition, inside a ...
65 views

### Commutative algebra by generators and quadratic relations

My apologies if this has been asked before. Please also be gentle, as this is my first question here. I am trying to define a commutative algebra by generators and relations in the following way. ...
68 views

### Manipulating infinite series

If I type Sum[f[x],{x,m,Infinity}]-Sum[f[x],{x,m+3,Infinity}] I would like Mathematica to return something like ...
322 views

I'm trying to register (align) two circular grayscale images using a boolean mask to prevent them simply being aligned on the fixed circular border. There are also small fixed circular regions in the ...
46 views

### Aborting Multiple Trial Divisions if a Factor is found

I am using Mathematica to perform trial divisions on large Mersenne numbers using specific prime numbers (e.g., primes of the form 8n+1 or 8n-1) and would like the program to abort once a factor is ...
77 views

Going through Derbyshire's Prime Obsession & trying to take LogIntegral of 20^ZetaZero[1] & comes up with a value of ...
882 views

### NonlinearModelFit does not find a good fit

I am trying to fit my data to the following function, $$\frac{a b t \left(\log \left(\frac{-a d t+a t-1}{a d t}\right)-2\right)}{4 (a t-1)}-c$$ ...
95 views

### Increase optimization processing speed

As you know, sometimes numerically solving of optimization problems takes several minutes. For this reason 2 question came up to me: 1 - When one is abort the optimization procedure, how it is ...
75 views

### Control Object Annoyance

This may seem like is a trivial annoyance, but it really is a control object "convenience of use" issue. Example: I want to use a popup menu to determine which Excel worksheet I take data from, as ...
480 views

### How can you convert a matrix back into a list of lists?

It is very simple in Mathematica to convert a list of lists into a matrix: all you need to do is apply the //MatrixForm function to it and voila. Is it possible ...
147 views

### How to inherit options by scoping?

Consider the following example: you have a function framed producing a cell with a button that, when pushed, calls framed again. ...
145 views

### How to fill a whole rectangle with text?

I have a rectangle with specified dimensions and I'd like to fill it with text, so that the text uses all (well, as much as possible) of the available area. I tried to do it with ...
325 views

### Re-arranging / selecting of a data table very slow in For loop [duplicate]

My task is quite simple; I have a table of data like M = {{1,2}, {1,3}, {3,4}, {5,1}, {6,9}, {6,8}, {6,1}}; so the table is sorted with respect to the first ...
177 views

### NDSolve with varying PrecisionGoal and WorkingPrecision

Sometimes we need higher numerical precision to deal with large number cancellation in an equation. But if this cancellation happens only in a small (and known) parameter space, would it be possible ...
176 views

### Floating point addition not associative

Can anybody explain the following behavior? x = 0.2 + (0.3 + 0.1); y = (0.2 + 0.3) + 0.1; x == y (* -> True *) But actually the variables do not exactly ...
62 views

### Dot shading a.k.a. Stippling effect [duplicate]

I am trying to convert grayscale images to black and white, where I hope to have certain artistic effect, called stippling: I have tried two methods; dithering (with ...
137 views

### How to export data in scientific form

I am having an issue about how to export data in its scientific form using Mathematica. To be concrete, I define a list ...
459 views

### Testing for OLS Heteroscedasticity White's General Test

I've done my best to search the help and google White's test (http://en.wikipedia.org/wiki/White_test) in Mathematica. Can anyone point me to a function or Mathematica reference for this or do you ...