4
votes
1answer
172 views

Using Mathematica's Position Function

I have a list a = {-1, 2/3, -2 - 4 I, -2 + 7 I, 2 I} and when I use the Position[a, I] it returns ...
2
votes
2answers
91 views

None of the NMinimize methods leads to the answers of the equation

The following 10 equations has one set of exact answer using NSolve in Mathematica 9.0.0.0 (for positive c2, alpha1, alpha3, beta1, beta3, A1 and A3): ...
3
votes
1answer
58 views

Annotating output without changing the value [duplicate]

I like to annotate output, using something like the following: ...
1
vote
2answers
110 views

depicting specific element of a table (knowing its position) in different color

there is some 20 Time 20 tables, in each step we choose one element randomly. how can show this random selected element with different color?
0
votes
1answer
70 views

Getting error from CommunityGraphPlot

Situation I'd like analyse my web site with CommunityGraphPlot as follows: Step 1: Define a function to scrape the all the webpages from expected website. ...
2
votes
1answer
34 views

Specifiying values in a system of equations

Suppose I have system of equations, for example Clear[a, b, c] Reduce[{RCI7[{a, b, c}] > 0, RCI7[{b, c, a}] > 0, RCI7[{c, a, b}] > 0}, {a, b, c}] // N ...
0
votes
1answer
49 views

How can I prevent exponents from appearing in an expression?

I've found posts dealing with showing/hiding exponents for numbers, like in scientific notation. But what if I have a general expression? I have an expression like this, ...
3
votes
1answer
165 views

Animating magnetic field lines on a circle

So I want to create a changing vector as a function of theta and have it's origin stay on the path of a circle. The vector I want to plot is: ...
0
votes
2answers
53 views

Please, can someone solve this equation [closed]

Solve the equation: e^(at)+e^(a(t-T)) = 2. Please can someone help me to solve this equation. I need a in terms of t, T.
1
vote
1answer
65 views

Error with NDSolve when used for a nonlinear system of PDE's

I am trying to solve the following system of Hamilton-Jacobi PDE's: $ V_1,_t - 0.5 V_1,_x^2/(1 - 0.2x)^2 + V_1,_x(0.1x^2+0.03x+.0.01)/(1 - 0.2x)+0.03(x-0.5)^2-V_1,_x V_2,_x/(1 - 0.2x)^2=0$ $ V_2,_t - ...
1
vote
2answers
78 views
0
votes
1answer
117 views

Reflective and Constant Flux Boundary Conditions

Can anyone tell me how I can use NDSolveValue to model reflective and constant heat flux boundary conditions. I am solving the heat equation. Essentially I have a ...
2
votes
1answer
41 views

N-Dimensional vector from scalar

Is there a way in Mathematica to create an n-dimensional vector, where each element is a given scalar? I have tried the Array function, as the documentation center ...
9
votes
1answer
203 views

What is FrontEnd`AttachedCell?

Perhaps it's not accessible from the front end, but what is this so-called attached cell? ...
1
vote
2answers
87 views

Maxima turn out to be false maxima when extremising function locally

In short: I have a 2-D function that gives this plot, where the orange dots are maxima: There are 4 maxima in this plot. Now, I plot the function again in a smaller region, close to these maxima, ...
1
vote
5answers
370 views

How to repeat a string?

I really can't find a way how to multiply (repeat) strings in Mathematica. How to write this shorter? ...
0
votes
1answer
39 views

Why this throw Null^2 Return[e1]? [closed]

I am amazed by the difficulty of Mathematica, due to my OOP background. Why does the following code not return the output I am expecting? ...
1
vote
1answer
70 views

What is the shortest way to make a lot of plots with different axes for the same data?

I am trying to make my code readable and nice. My functions are ...
2
votes
2answers
150 views

Refining subset relations

People who do combinatorics (like me) are often faced with the following problem: For a list of combinatorial objects (vectors, permutations graphs,etc.), we know what multi-set of values it ...
2
votes
1answer
48 views

Add text label in the top-left of a TableForm

I have a function that should give a multiplication table for an integer input: TableForm[Outer[Times, Range[#], Range[#]], TableHeadings -> Automatic]& ...
-1
votes
1answer
111 views

How to input functions into Mathematica [closed]

I need help with this assignment like asap. I've never been taught how to use this program and our math department expects us to learn how to use it, but it is just so complicated!!! Please help me ...
2
votes
0answers
64 views

Where do the radicals end?

In an early iteration of this question on the Mathematics SE, the radicals weren't properly formatted, so they only had the √ symbol with no indication of which terms were supposed to be ...
2
votes
1answer
162 views

Simple code to write differential equations in a matrix formulation

Is there a simple code to transform the following differential system equations : ...
1
vote
1answer
99 views

Find function tracing the maximum of a 2D function

I'd like to solve the following problem: Given MI[o_, n_] := Log2[1 + 4 o (Sqrt@n + Sqrt[1 + n])^2] Find a function f[n_] ...
2
votes
2answers
72 views

Problem with ArrayFlatten to concatenate matrix

I would like to concatenate 2 matrix : - the first which is a line of 2 elements - the second which is a matrix of 2-2 elements I use the following code : ...
31
votes
1answer
842 views

Terrifying performance decrease for contour/density plots in v10.1 -> 10.3

Bug introduced in 10.3 and fixed in 10.3.1 I setup for download a test dataset at http://www.inrim.it/~magni/cm.dat.gz (a set of 64800 triplets x,y,z). The behavior can be reproduced with the ...
2
votes
2answers
131 views

Why do the boundaries from RegionPlot not match the contours from ContourPlot?

When I try to plot a 2D interpolation, coloring areas with RegionPlot and adding contours with ContourPlot, the boundary given ...
2
votes
1answer
154 views

Fitting to the system of equations with no analytical solution

I'm trying to fit linear combination of 2 functions to my experimental data set (it represents voltage of 2 photodiodes - Voc1 and Voc2 - connected in series under illumination - S) ...
1
vote
1answer
309 views

Calculating the normalization constant for a wavefunction

How can I compute the normalization constant for a quantum mechanics wave-function, like $\Psi(x) = N \exp(-\lambda x^2/2)$ by using Mathematica? (The normalization constant is $N$).
1
vote
1answer
54 views

Problem averaging multiple series of data [duplicate]

Recently I'm having trouble figuring out a certain problem in Mathematica. I have a table of data in the following arrangement: {series no., x, y} Now, each series of data has exactly the same x ...
4
votes
1answer
86 views

Draw lines between all neighbours

I have seen this question, but what I want is a bit different. I have a set of data (blue points) and I would like to end up with something like this: , i.e. joining each site with all its ...
4
votes
1answer
92 views

What is a sufficient decrease in the merit function?

As far as I understand, the merit function measures how far the data is from the fitted function. I am calulcating the second partial derivative of a function, and then numerically finding its maxima ...
0
votes
2answers
62 views

Numbering the elements of a list

From a vector q={Gamma,x,y}, I would like to create the following corresponding list : qn={1,2,3}. Other example, if I have ...
4
votes
4answers
165 views

Numeric range: present or not

There is a formula to test whether a number is included in a range? For example, if 3 is between -2 and 6.
1
vote
2answers
111 views

How to update values in an Association using a pattern?

Say, having an association: asc = <|"a" -> 5, "b" -> 4, "c" -> 21|> I can updated values like: ...
0
votes
1answer
72 views

a question about Nminimize [closed]

I have 10 equations and 10 unknown parameters such as alpha1,alpha2,a1,a3,... which I want to find them by minimizing ...
1
vote
1answer
57 views

Error in NDSolve

I want to solve this nonlinear equation in the "NDSolve". The matrixs of this equation are defined as below. ...
2
votes
1answer
54 views

If I want a function only applies to the elements of a specific list, how should I define the function? [closed]

If I define a list: list={1,2,3,4}; and I want a function f to apply only to the elements in the list (for here it is ...
0
votes
1answer
130 views

Crash when dynamically updating ListLinePlot

I was trying to solve a wave problem using numerical methods. The code below crashes each time I run it on Windows with version 10.2. ...
4
votes
2answers
164 views

How to find analytical expresion for data from image

I need to find an analytical expression for the data collected from an image. I found a relevant topic on how to extract the data in here. But there are some differences in my question. I have this ...
1
vote
1answer
59 views

Simplify the following transformed equation [closed]

y=7f(-1/6(x-1))+1 The base function is f(x)=x^2. I just don't understand where the ^2 went and how to simplify this. Any help is much appreciated, thanks.
4
votes
2answers
79 views

N not behaving in the way I expected it would

I'm trying to use the N function to find the percent error between a function and a rounded value of that function. The code looks something like this. ...
7
votes
3answers
168 views

A replacement question

I have: {{θ -> 0}, {θ -> (2 π)/ 3}, {θ -> π}, {θ -> (4 π)/3}} I would like to create a list of points $(\cos\theta,\sin\theta)$ using each of the ...
4
votes
1answer
76 views

How to get a 2D Plot from a 3D plot?

I have the following code below, that relates Concentration C[x,t], Time [t] and Space [x]: ...
5
votes
2answers
63 views

Parallel execution of an instructions block

I regularly use Parallelize and ParallelMap, andI've been reading the manual pages for parallel computing instructions but i could not find what I am looking for. Assume I have a sequence of ...
2
votes
1answer
55 views

Differential of constraint equations

I have the following constraints equations : SysCon = {-(1/2) l Cos[γ[t]] + Subscript[x, G][t] == 0, -(1/2) l Sin[γ[t]] + Subscript[y, G][t] == 0} I would ...
27
votes
3answers
504 views

Cyclic Take function? [duplicate]

Is there some direct and simple "cyclic Take", sometimes also known as "overtake" in Mathematica. That is, if the take specification runs out of elements, it just cycles back to the beginning (as many ...
1
vote
1answer
71 views

Solution of Inverse parametric implicit functions [closed]

Using NDSolve I solved for functions $G={x,y,u,v}$ that are functions of $t$ \begin{eqnarray} y'(t) &=& f(x) \\ x'(t) &=& g(y) \\ u'(t) ...
4
votes
1answer
52 views

apply a constraint to summation limits

I have a list as list={{-0.5, 5}, {-0.25, 2}, {0, 3}, {0.25, 2}, {0.5, 5}} and I want to use of Esc+sum+Esc symbol for ...
8
votes
1answer
94 views

Understanding Part and Span operating on expressions with heads that are not List [duplicate]

I hope this is not a duplicate. I do not understand how does the Part and Span functions work on this expression: ...

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