# All Questions

176 views

### Given a matrix of integer, create a matrix with 1 or 0 according to which numbers are in the first matrix

Not sure the title gives the idea of what I need, so here is a sample: I have ten (w) combinations (subsets) of 20 (n) numbers taken 4 (k) at time. I need a matrix of dimension w x n with 0/1 in each ...
137 views

### Split/unmerge merged cells in notebook file

I have merged cells in a Notebook file. Is there a way to split such a merged cell group back to single cells, in each of them being one command?
70 views

### NSolve not solving [closed]

I've been working on a Newton Cooling equation problem for my diff equ class and cannot get NSolve to solve this equation. I've plugged it into Wolfram Alpha and my ...
249 views

### How to solve time dependent coupled differential equations using Floquet method?

I have coupled differential equations D[X[t], t] == M[t] X[t] + R[t] where ...
144 views

### Large data -list contour plot -list log plot

I've a large data make matrix 100*100 and and other two sets of data represent the x and y axis. Each value in the matrix is a related to one value in x and one value of y. I ask about a way to plot ...
89 views

### Displaying Greek letters with subscripts inside plot [duplicate]

I am using ListPlot: ...
911 views

### Finding number of pixels with certain RGB color in an image

I have the following image: To determine the number of black pixels (nBlackPixels) I use: ...
77 views

### How can I move the x-axis label beneath (instead of at the end of) the x-axis?

I borrowed this code from a Wolfram demo. I looked at several answers to the general question of how to move the x-axis label from the end of the x-axis to beneath it (use ...
122 views

### Write list of numbers to a file

I have a list of numbers: e.g. list={1,2,3,4,5} To write the list to a file I use (here each integer number occupies 7 spaces): ...
52 views

### Plotting based on all previous equation results [closed]

I have a plot Plot[40500*x^(-0.1), {x, 1, 100}, PlotRange -> {0, 50000}] Now, I am trying to plot the cumulative of these y values. I'll try to explain on an ...
163 views

### How to convert a rational parametric plane curve into implicit form?

This problem is generated from another Green's theorem related question of mine. And here is a forward of the same problem in math.stackexchange. The original equation of the plane curve is not in ...
481 views

### How to Find “n” for n-th Triangular Number

For example, the 7th triangular number is 28. How do I create something that will tell me that 28 is the 7th triangular number? This is what I have created. ...
339 views

### How can I smooth a 3D surface generated by RegionBoundary?

I have a set of points that belong to the surface of an object. I would like to approximate a surface to which I can compute the distance. of other points. With the nice code of this post, I was able ...
200 views

### How can I convert a fraction to a string that can be used in a file name?

I want add an index to the file names of my exported images, so I'm using ToString. But I have a problem when my index is a fraction, because then the generated ...
103 views

### Mathematica computes wrong eigenvectors? [closed]

I have a matrix M = {{0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, b}, {0, 0, -b, 0}} that I want to diagonalize. So far, I always used the following and it worked, but ...
184 views

### How to Write Partition with Infix?

The documentation says that using Infix ~, the following input f[e1,e2,e3,...] can be rewritten as ...
178 views

### Problem with NDSolve: derivative interpreted as square [duplicate]

I am using Mathematica 9, and trying to solve a very easy differential equation with NDSolve. The code I have is s=NDSolve[{y'[x]==y[x],y[0]==1},y,{x,0,1}] but I ...
215 views

### Help me export high-resolution TIFF figure

I have generated a figure in MMA by ContourPlot3D. How can I export this figure in high-resolution TIFF format(say, 1200 dpi for lines, 300 dpi for halftone and ...
107 views

135 views

### Converting integral equations to differential equations

I am trying to use Mathematica to convert integrals to differential equations, of any order. An example of an integral equation is given below, in Mathematica code. Could you please advise as to the ...
104 views

### How to remove multiplicities from for a list in way meeting special criteria

I have a list of pairs, tabul, which has the property that the second element of each pair is also an element in my list data. I ...
1k views

### my Mathematica has turned orange and not able to find out why

I do not know what happened. But when I rebooted my PC, now Mathematica comes up orange colored. I shut down the PC and tried again, it is still orange. Here is screen shot: I also did a reset. ...
167 views

### Plotting a set of points given by a complex expression [closed]

A have the set consisting of the complex numbers $1+3r \cosθ−ir \sinθ$, where $r∈[0,1]$ and $θ$ may vary between $0$ and $2π$. This is my first encounter with Mathematica, and am having difficulty ...
91 views

### Compute complete graph and make minimum spanning tree

I'd like to plot a complete Graph and then compute the Minimum spanning tree of it. I already can make a complete graph out of a list that countrydata gives me: ...
508 views

### How to export images in EPS format that can be opened in CorelDraw

I am preparing a paper. The journal requirements are odd: only eps files for pictures are accepted. All pictures I have drawn in Mathematica and exported in eps format in the usual way: ...
88 views

### Comments including LaTeX commands in Mathematica [duplicate]

I want to write some comments in Mathematica - which include LaTeX commands - using the form ...
232 views

### How to check the option value?

Given that I have a function func as follow: To check the value of options, I using the step-by-step method If[] ...
340 views

### How to Apply Functions to Lists with Many Curly Brackets?

For example, consider the list defined below. samplelist = {{{1,2,3,4}}, {{5,6,7,8}}}; How would I apply the Times operator ...
83 views

### Functions becoming undefined when evaluated

I'm so confused I don't even know how to phrase my Question title. My function nextCol works until I use colLength, then ...
85 views

### Faster use of Condition for a large array (see the example)

Here is the example/problem. I have a array of $n$ random number. n = 2000; p = RandomReal[{0, 9}, n]; I have to create a $n\times n$ sparse matrix with $(i,j)$...
196 views

Example: ...
74 views

### Building up a sequence dealing with a complex recursive scheme

Suppose I have multiple lists, the first one contains 2 elements, the next one 4 elements, the next one 8 elements, and so forth. Let these elements be labeled as Gij where i refers to the list it ...
77 views

### Optimization over 6 vectors

Suppose I have an expression which depends on 6 unit vectors (3 dimensional). Hence, I need to optimize over 12 parameters (every vector contains 3 parameters, but one we can reduce by considering ...
149 views

### How to tell Mathematica that my variable is a scalar

In my calculations I have these combinations PauliMatrix[1].f PauliMatrix[2] where f is a scalar function. The result is as ...
103 views

### How to get the size of a specific image in the front end?

The title pretty much says it all. One possible point of confusion is that this question is not limited to items with head Image. I don't know what is the ...
153 views

### How to scale multiple graphics to preserve relative sizes?

I'm looking for a simple way to make the displays of different Graphics expressions accurately reflect their relative sizes. (By "simple" I mean that it does not ...
87 views

### Conditional subset generation

I am trying to accomplish the following task: Given a list of coordinates of n points in the plane, I need to find subsets of all points that share the same x-...