0
votes
0answers
37 views

Error message: ArcTan called with 0 arguments; 1 or 2 arguments are expected [closed]

sol = NDSolve[{y'[t] == E^t ArcTan[t], y[0] == 0}, y, {t, -100, 100}] Am I blind? What is wrong here?
2
votes
2answers
61 views

Sum broken into two sub-sums according to a condition on the terms

I have a sum in mind, but I want to break it into two sums and get a separate total for each of the two. All cases where the square root is accurate, i.e., exact All cases where the square root is ...
2
votes
0answers
43 views

FourierTransform of a gaussian at -1 and 2

Let ft[w_] := FourierTransform[Exp[-t^2], t, w] Then ft[#] & /@ Range[-2, 3] Evaluates to ...
0
votes
1answer
25 views

Transpose four lists of data into two lists for use in List Plot [closed]

I have four lists of data x1 = {1,3,5,7} y1 = {0,2,4,6} x2 = {10,12,14,16} y2 = {8,10,12,14} In one line is it possible to use transpose to get two lists which ...
3
votes
1answer
69 views

Eigenvalues function not producing expected results?

I'm running into a strange issue when trying to compute eigenvalues of a 2x2 matrix for graphene. If I "manually diagonalise" by multiplying the two off-diagonal terms together and taking the square ...
6
votes
2answers
200 views

Curvature Application

I found these amazing animations at https://courses.engr.illinois.edu/tam212/avt.xhtml#avt which I think will be wonderfully useful when teaching multivariable calculus next semester. I've started to ...
0
votes
0answers
53 views

Switching ArcTan argument from a sequence to a list

The objective is to determine the angle formed by the line connecting two points in the plane, say p and q. The ...
-1
votes
0answers
31 views

Turning something into a form that can be used as C code [closed]

I have a function F[x_]:= SOMETHING and I want to use it in a C code. Is there any easy way of doing this? Examples For functions like Log or sqrt, it could use the math library, for special ...
1
vote
1answer
50 views

Multiple lines in an If statement [closed]

What I am wondering is how do you perform multiple lines when using the If statement. I know the following is not proper Mathematica code, but how would I do this in Mathematica? ...
11
votes
1answer
148 views

What's wrong with Simplify and FullSimplify?

I have a quite complex list of equations and inequalities I combine to a boundary condition for my cost function. After investigation of two days I found the bug (I really name it a bug!). One of my ...
0
votes
0answers
62 views

PDE with Laplacian time derivative term

Using Mathematica 9 I am trying to solve the 2D PDE: c1*Laplacian[-u[x,y,t],{x,y}] + c2*D[Laplacian[-u[x,y,t],{x,y}],t] == 0 (Eq.1) with time-dependent Dirichlet ...
0
votes
2answers
84 views

Examining the equations of a Differential Op Amp

I want to examine the equations of a differential Operational Amplifier, specifically I want to examine how the tolerances of the resistors affect the resulting differential gain and common mode ...
1
vote
2answers
60 views

How to tell Mathematica that a limit converges to a product of two variables

I have looked through the manual and Im simply just stuck trying to make Mathematica solve this: ...
0
votes
1answer
42 views

NDsolve with discontinuous non-numeric PDE coefficients

I want to solve the heat diffusion equation with variable thermal conductivity. So I have the following code ...
1
vote
0answers
26 views

Method used by NMaximize with a binary linear problem

I'm using Mathematica 7's NMaximize to solve a linear programming problem with thousands of 0/1 integer variables, thousands of linear constraints and a linear target. I suppose I could use ...
8
votes
1answer
171 views
4
votes
3answers
125 views

How to get multiplication of the elements of a specific list/Matrix

Assume there is a list: List1={a,b,c,d}; Then I want to get these calculation: ...
1
vote
0answers
46 views

Change only tick labels while keeping default ticks [duplicate]

Consider the following Plot3D (although the same question might be asked for the 2D case) ...
2
votes
1answer
139 views

Where I can find the CD version of Stan Wagon - “Mathematica in action” 3rd ed. book?

I've just started my license and I need the code to focus on implementing my programs. I can't make the code in the book run. Can anyone help?
1
vote
1answer
38 views

How to change the position of the PlotLabel? [duplicate]

PlotLabel positions the label on top of the plot by default. I would like to put it below the plot. How can I do that? Thank you.
0
votes
0answers
37 views

NDSolve : Solve a single variable-coefficient ODE as series of constant-coefficient ODEs

I have a manipulator equation of the form: $M(q){q''} + C(q,q')q'+G(q) = {0}$ where $M, C$ are $6$ x $6$ matrices, and $G, q$ are $6$ x $1$ vectors and $q$ a function of time. ...
0
votes
1answer
31 views

EdgeForm with Graphics

I want my figure to have an edge and I am playing around with EdgeForm[Thick], putting it in different places. My figure is: ...
0
votes
0answers
56 views

Small difference between large numbers [closed]

I would like to calculate the difference of the two large numbers, which are close together. See here my (sorry, quite long) code: ...
0
votes
1answer
50 views

Obtain constant from DSolve [closed]

I need to extract constant C[1] from expression which I get when solve equation. i.e. DSolve[y'[x]==1/(2x),y[x],x] In result Mathematica gives me this one ...
1
vote
0answers
53 views

Custom Head for Encapsulation

Often when I'm writing a project in Mathematica, the number of arguments I must provide to functions spins out of control. I need a sort of object-oriented encapsulation approach. I've already had a ...
4
votes
0answers
76 views

Is there an elegant way of delaying evaluation of `A==B` when calling a function that uses this pattern

Suppose I wanted to define a number of functions that accepts expressions of the form: ...
4
votes
4answers
419 views

How to create a thick spiral then extract the coordinates from the image?

I can plot a thin spiral using just: $ r=\frac{\theta }{2 \pi };$ PolarPlot[theta/2 Pi,{theta,0,2 Pi}] but is there a way to plot a spiral that has actual area ...
3
votes
2answers
98 views

Find the area of a contour surface plotted by ContourPlot3D

I am looking for a way to find the surface area of a contour from ContourPlot3D. Here is an example where I might like to find the area of the contour surface to ...
0
votes
1answer
76 views

How to efficiently compile this function? It involves a 3-index Table [on hold]

Consider a 2-dimensional lattice with LxL sites. Each site has 4 neighbors, and we can then define a function (called below ...
0
votes
0answers
42 views

Plotting complicated function with not exactly defined angle [closed]

I want to plot the time-averaged electric energy density near the focus according to Boivin and Wolf. Now I have my three intensities. I am very new to Mathematica and my problem is that I can't ...
11
votes
2answers
221 views

Trainable WEKA segmentation of images

Is there a Mathematica equivalent of Trainable WEKA Segmentation as implemented in Fiji, the image processing software? A Google search did not return any relevant links. I attach the original image ...
2
votes
0answers
30 views

How to get simultaneous eigenvectors of commuting matrices? [duplicate]

So let's say there are two square matrices A and B that commute (AB-BA=0). This implies that there must exist some complete set of vectors that are eigenvectors of both A and B. Is there any way to ...
4
votes
1answer
74 views

What options need to be set for Simplify to perform a certain manipulations similar to FullSimplify?

Simplify performs algebraic transformations and is fast, while FullSimplify tries a wide range of transformations involving ...
0
votes
1answer
56 views

Evaluate NDSolve within NDSolve

So I am attempting to solve a differential equation which includes a differential equation (i am not sure if this why my code is giving problems). I am pretty sure that everything is as its supposed ...
0
votes
0answers
53 views

OLS Estimation - Computational results vs. calculation by hand [closed]

I calculated the OLS estimators for a data set by hand using $$\hat\beta=(X^TX)^{-1}X^Ty$$ If I check my results with Mathematica I get different results. I'm quite sure that I didn't make any ...
0
votes
2answers
31 views

How to get Complement function working in a For loop? [closed]

I've been working on a piece of code that will delete small components from a nested uneven matrix (n pages, n rows, 3 columns), by deleting the pages with less than ~30 rows. However, I've notice ...
1
vote
1answer
34 views

Can I rely on the ordering of the adjacency matrix? [closed]

Suppose I have created a Graph[{1,2..n}, {1->3, etc}], and I take the adjacency matrix of that graph. Can I rely on the fact that the i-th entry in the graph is the i-th node in the matrix? Or maybe ...
1
vote
0answers
43 views

Does a matrix need to be rationalized when calculating MatrixExp? [closed]

I have a sparse matrix, L, and need to calculate its exponential, MatrixExp[L t], where t is ...
1
vote
2answers
152 views

Having trouble translating Matlab `fsolve` into Mathematica

I searched the site and found that someone said FindRoot is equivalent to fsolve, however, without proper options, ...
3
votes
0answers
53 views

Simple ways to implement vector dilation

Suppose we have a singly connected but not necessarily convex polygon. Something like shape = CountryData["Chad", "Coordinates"]. Is there a simple way to ...
1
vote
0answers
56 views

How to freeze and test a list of programs?

I have a list of problems for my students and I'm trying to use the new v10 feature TestResults like so: ...
1
vote
0answers
35 views

DSolve -> no results

I am trying to solve a system of differential equations. ...
6
votes
2answers
132 views

Import data from excel and store it permanently in notebook

I am trying to write the code for doing the following: by clicking a button, import specific data from an Excel file which I select through a dialog window; input a name for the imported data set ...
4
votes
1answer
197 views

Why don't the arrowheads show for this directed graph?

It's very weird, but the first graph is shown as undirected (dots connected by lines, not arrows. The second is shown as directed, with arrows. I'm using the cloud version of Mathematica. ...
3
votes
1answer
53 views

Assign values to parameters from a list/Matrix using GUI

Assume there is a list like: ma={{L1,r1},{L2,r2}}; I want to convert the ma to a GUI which asks me about the values of ...
0
votes
0answers
29 views

rgb2ycbcr and ycbcr2rgb performing twice on same image gives different answers? [closed]

I converted an image from rgb to ycbcr using rgb2ycbcr. Then converted back to rgb using ycbcr2rgb. Again converted the resulting image from rgb2ycbcr. But in the first and second rgb2ycbcr ...
2
votes
1answer
31 views

problem exporting an Animate video

Here's my code: ...
5
votes
1answer
66 views

Customized FortranForm output

Let's take the following example V = (-G*Mn)/Sqrt[x^2 + y^2 + z^2 + cn^2]; Vx = D[V, x]; FortranForm[Vx] The result is ...
15
votes
1answer
263 views

Implicitly defined compact complicated surface

A Seifert surface for the (3,4) torus knot is defined by the intersection of $S^3 \subset \mathbb{C}^2$ with the set $\arg(z^4-w^3)=0$. The boundary is at $z^4=w^3$ and this is the torus knot. Here ...
2
votes
2answers
56 views

Export NDSolve results

I can see the correct result of my NDSolve when I plot them with large PlotPoints. ...

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