5
votes
4answers
253 views

Picking numbers within a list with an interval of 60

I have a list of integers from 1 - 400. I choose n random numbers with replacement from the list. Here is an example: ...
2
votes
1answer
474 views

Problem with Covariance Matrix Output in NonlinearModelFit

I am running NonlinearModelFit based off of some simulated data and trying to fit to a function with more than one parameter. Eventually, I would like to fit to 5 ...
1
vote
0answers
93 views

what is the difference between these definitions? [duplicate]

I define 2 functions: g[s_][x_,y_] := the gaussian (1) g1[s_,x_,y_] := the gaussian (2) I get the same answer using ...
9
votes
2answers
444 views

Intersection for lists of numeric data

I know that Intersection is a pattern matching function and will not evaluate list elements to determine if two or more list have equal elements. So my question is, ...
5
votes
1answer
244 views

Using the keyboard to interactively and dynamically specify coordinates in a grid (a la Battleship board game)

In Mathematica, it is possible to create a Table or Grid of \[Placeholder] boxes. For ...
3
votes
1answer
339 views

Importing numerical values from a PDF file

I need the numerical values from pdf files like this one. When I use the usual Import command, the PDF imports, but pages of images. How can Mathematica be used ...
0
votes
2answers
205 views

Unexpected complex roots from solving a cubic

I am new to Mathematica and there is a behavior that I don't understand. When I insert the code: Solve[-(x - 2)^3 + 10 x - 10 == 0, x] I obtain: ...
4
votes
1answer
484 views

How can I deal with a non-numerical value for a derivative at $t = 0$ when using NDSolve?

I want to solve two coupled equations with NDSolve, ...
2
votes
2answers
181 views

Trigonometry expansion of a product

The following command does what I want: ...
1
vote
1answer
160 views

Optimization for inequalities in $\mathbb{C}$

I want to check when the expression $$ \sqrt{\sqrt{\lambda^{2}\left(2E+\lambda^{2}\right)}+E+\lambda^{2}} $$ is real, when it is purely imaginary and when it is complex (with imaginary part not ...
3
votes
2answers
550 views

Optimization problem with matrix positivity constraints

Is it possible for Mathematica to parametrically find a local minimum of a given function (say of some variable $x$ where $(a,b,c)$ serve as parameters) subject to the constraint that a given ...
1
vote
0answers
213 views

Variable scope in nested NMaximize, NMaxValue

I'm trying to use NMaxValue inside other statements (FindRoot and NMinimize). Those statements should bind variable names, but I'm getting weird warnings which seem to indicate that the variables ...
1
vote
1answer
1k views

Computing the fundamental matrix and its monodromy matrix

Assume $\dot x(t)=v(x,t)$ is a $T$-periodic, with respect to $t$ dynamical system. That is: $x\in\mathbb R^n,\quad t\in\mathbb R,\qquad v(x,t+T)=v(x,t)$. Let $x_0$ be a smooth periodic solution in ...
6
votes
1answer
451 views

Using MathKernel without echoing a window

I use M9 under windows 7 on a command prompt as: MathKernel -noprompt -script file.m On execution, there is a like a kernel window opened and then closed immediately. How can I avoid this window and ...
0
votes
0answers
154 views

How to add labels to a graph [duplicate]

This should be an easy question but since few examples are given for ShowLegend and I am a new user, I got stuck after many attempts. I plot three graphs which are ...
0
votes
1answer
1k views

How to neglect higher power terms in a polynomial expression

I have a polynomial expression of order n (say n=20). F(x)=1+x+x^2+x^3++...x^20. I want to approximate the polynomial for order 3 only. So I need to make the ...
1
vote
1answer
172 views

Manipulate doesn't work for plotting a region where a matrix is positive semi-definite

I'm facing the following problem and would very much like you help. Thanks is advance! I have defined the following 4x4 matrix: \begin{equation} S=\left( \begin{array}{cccc} ...
-6
votes
1answer
475 views

random number visualization without generator (Spectral Test) [closed]

Does anyone have codes for using only numbers to make this kind of random-number visualization and not requiring a number generator? ...
6
votes
2answers
416 views

Pruning elements in an array based on the existence of similar elements in adjacent arrays

Imagine I have a series of particles floating around in $\mathrm{R}^3$, where, at any given time, particles can pop into and out of existence. Here, for some number of time points, $(t_1, \dots, ...
5
votes
3answers
623 views

ContourPlot and Colorfunction

I have the following code: ...
1
vote
0answers
75 views

ReadList with type Expression unable to read scientific notation? [duplicate]

I have a file that defines an array of numbers like this: freq["AQs"] = 8.846947803007962E-4 ... I am reading the file with ...
0
votes
1answer
114 views

Conditioning on group of functions

I have two sets of functions which I want to implement them in a single function with an option indicating which set of functions should be used. Suppose that I have two lists like:(updated example) ...
11
votes
3answers
471 views

How to make Excel-like data bars?

I would like to make a grid where each cell background is partially filled according to the numerical value being represented (on a scale from 0 to 1). Similar functionality to the one requested in ...
6
votes
1answer
2k views

Mutual Information involving two matrix states

I basically retrieved the following technique of evaluating the mutual information involving two matrices from this site at http://bmia.bmt.tue.nl/People/BRomeny/Courses/8C080/default.htm The ...
6
votes
5answers
229 views

Lowering the degree of an polynomial with an assumption that the polynomial has a factor x^2+ax+b

Let's assume $ x^{10}+x^5+1 $ has a factor $x^2+ax+b$ Then, If $x^2=-ax-b$, $ x^{10}+x^5+1 =0$. If we successively apply $x^2=-ax-b$ to $ x^{10}+x^5+1 $, we can make $ x^{10}+x^5+1 $ to degree 1, ...
9
votes
1answer
1k views

FourierTransform and Partial Derivatives?

I have a function of three variables $f(x,y,z)$, and it obeys a linear partial differential equation. I'm checking my by-hand calculations with Mathematica. I want to convert the PDE into the ...
3
votes
1answer
932 views

Simplifying an ArcTan expression

The expression $\tan ^{-1}\left(\frac{\sqrt{L^2 \sin ^2(\theta )}}{\sqrt{L^2 \cos ^2(\theta )}}\right)$ can be simplified to $\theta$. After some attempts I got the following to do the job. ...
1
vote
3answers
995 views

Phase portraits and StreamPlot

I typed StreamPlot[{y, x-x^3-0.3y+0.5Cos[1.25t]}, {x, -2.5, 2.5}, {y, -2.5, 2.5}] but all I got was a blank plot. What did I do wrong and can I fix it?
26
votes
6answers
622 views

Constructing symbol definitions for With

I would like to be able to define two arrays, one containing symbol names and one containing the values of those symbols, for use in constructs such as With. For ...
8
votes
4answers
548 views

Gather list elements by index

The following list has some elements that are labeled. For example {1, 2} -> 1, {-1, 3} -> 3, etc: ...
1
vote
1answer
552 views

How to tell Mathematica not to simplify an expression

While there is this question with a very similar title, it does not answer my question, which is: I have part of an input, in my case Re[Exp[I*x]] which ...
3
votes
2answers
317 views

two histograms ratio

I have two histograms and using listplot to draw both. Now, I want to draw a second plot, below the first, with the ratio of each bin. Does anyone know how to do this? Many thanks. This is the code ...
20
votes
4answers
2k views

How to get rid of the perspective effect in a 3D graphics

I have plotted a figure of MoS2 crytal structure. But the actual output looks like the spheres are not in the correct position due to the perspective effect. I obtained the correct position figure ...
-1
votes
1answer
121 views

How can I format DisplayFormula Cell into TraditionalForm when export as HTML

This example is in DisplayFormula cell. ...
4
votes
1answer
188 views

Modified definition of Sin does not work in Plot

I don't know if this issue has been discussed before, if anyone know any related post, please let me know, thank you :) Unprotect the function ...
6
votes
2answers
247 views

How can I use Pick to select items in one list when a value in a corresponding list is $\leq$ some value?

Imagine I have two lists: List1 = {0, 1, 0.6, 0.5, 1.2, 0.4}; List2 = {"a", "b", "c", "d", "e", "f"}; How can I use Pick to ...
2
votes
0answers
48 views

How can I account for assumed X and Y errors when using findfit? [duplicate]

I'm using very noisy biological data, and I need to assume, when doing linear regression, that there are errors in both X and Y. ...
1
vote
1answer
109 views

Eliminate some temporaries from a set of equations

I have a long set of equations, mostly obtained by introducing physics related quantities which stand for some kind of temporary variables: ...
5
votes
3answers
404 views

Switching among view points in a Manipulate expression

Edit: Some additional viewpoints were included to make it easier to test. Here's code for an alternative function, the graph of which is a bit less symmetric. Feel free to use either code set: ...
0
votes
2answers
167 views

Create a Matrix out of two matrices

I have two matrices A = {{a1,a2},{b1,b2}} and B = {{x1,x2},{y1,y2}}. I would like to create out of these matrices a new matrix ...
1
vote
1answer
318 views

Using Collect to gather explicitly imaginary terms

Collect[Expand[(x + I y)^6], I] yields x^6 + 6 I x^5 y - 15 x^4 y^2 - 20 I x^3 y^3 + 15 x^2 y^4 + 6 I x y^5 - y^6 How can I ...
3
votes
1answer
217 views

MathLink and writing *.tm files

My goal is to use MathLink to access the functions in sofa (Standards of Fundamental Astronomy) So far I have had mixed success. I have very little C programing experience so I am hoping to get ...
0
votes
2answers
95 views

Generating equally distributed voxel points based on a given point

I have a list of seed points that each of them indicates the bottom-left value of a voxel. In order to improve the accuracy of my function, I need to equally sample my points and apply my functions ...
3
votes
0answers
96 views

Finding the argument set for internal functions in Mathematica v9.0

I've recently run into a problem with importing TIF stacks in Mathematica: Slow import of multigigabyte TIF image stacks On the advice of Simon Woods and others, I've been looking into the behavior ...
7
votes
1answer
243 views

Symbolic tensor simplifications and the identity matrix

How can I get Mathematica to simplify the following expressions, with $Assumptions including Element[n,Integers], n > 0, and ...
5
votes
2answers
1k views

Place plot markers in front of error bars with ErrorListPlot

I'm making an ErrorListPlot where the error bars are a different color then the markers and it works, however, the error bars are drawn in front of the markers and ...
1
vote
0answers
312 views

Making simultaneous equation solving more efficient

I am trying to solve a system of several simultaneous equations that have been generated by a series of modules and functions, using this module: ...
0
votes
0answers
34 views

Applying Some Kind of Timing Function to AutoRunSequence [duplicate]

Ok, so I'm exporting a video to MOV format that is coming from a manipulate function (I'm demonstrating CLT to a class that doesn't have calculus as a pre-req, if anyone is curious). Anyhow, I'm ...
0
votes
0answers
46 views

List elements and iterator name collision [duplicate]

Let there be two lists, exp = {{i, i}, {j, j}}; exp2 = {{r, r}, {o, o}}; and there are two Table commands to access them. Then, ...
1
vote
1answer
65 views

Print all cells independently at once

Is there any way to print out to pdf file, in sequence, all cells independently? I have literally hundreds of cells that need to be printed in that way. Selecting each cell and "Print Selections" ...

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