# Tagged Questions

Use this tag only if you did your research and you still don't know why your syntactically correct code does not work.

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### ParametricPlot3D shows an empty box

I'm trying to visualize numerical solution of 4 differential equations (these are the coordinates of a wave function in a quantum mechanical system): ...
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### Inconsistency when adding a variable to an analysis

I have a system of three ODEs that I want to find the steady states of, and whether or not they're stable via a simple analysis. To do so, I just calculate the eigenvalues of the Jacobian evaluated at ...
116 views

### What is the Difference Between Rule (->) and RuleDelayed (:>)?

I am new to Mathematica so this question may seem rudimentary. Sorry for that! :) I want to implement the well-known property of Kronecker's Delta \Sigma_{i=1}^{n} a_i \delta_{ij}=a_j,\quad 1 \le ...
139 views

### NDSolve: Indeterminate expression 0. ComplexInfinity encountered? [closed]

The following code give errors that I don't understand. Could you please suggest a method to solve these differential equations? ...
33 views

### Second order differential equation, with term from previous numerical solution

I have a second order differential equation, in terms of a term that was previously obtained from numerically solving another equation. Numerical solution of equation before 2nd order equation: <...
107 views

### Solving cubic equation with unknown coefficients

I am trying to solve a cubic equation with unknown coefficients (p and t), here is the code: ...
82 views

### My program to model exterior ballistics doesn't doesn't produce the plot I expect

Here is my program to model exterior ballistics. It doesn't doesn't produce the plot I expect. How can I fix it? ...
63 views

### Lagrange multipliers implementation (beginner question) [closed]

I am trying to write a code to find the minimum of $f(x,y) = (Mx + Ny) \,/\sqrt{M^2 x + N^2 y}$?, subject to the constraint $g(x,y)=x+y-1$. Also, $x,y>0$, and $M$ and $N$ are positive constants. ...
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### Variable Definitions and Random Numbers [closed]

I have currently created the following matrix: m={{RandomReal[{0,1}],RandomReal[{0,1}]},{RandomReal[{0,1}],RandomReal[{0,1}]}} In other words, a $2 \times 2$ ...
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### Why different output is obtained for the same code (Mathematica 10.1)?

I wrote some code in Mathematica: ...
980 views

### How to set up a simple Monte Carlo Simulation

there is a 1% chance that there will be a scattering event, if there is a scattering event the direction of scattering will be determined by a random sample of the custom[a_] function and if there is ...
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### Wrong results from a branching function (ternary channel) [duplicate]

I'm doing one ternary channel and using the following code: ...
198 views

### Getting errors when I try to evaluate code taken from Trott's Mathematica Guidebook for Graphics

I would like to learn how to make high quality images in Mathematica. In my pursuit, I have come across Michael Trott's Mathematica Guidebook for Graphics. I have been trying some of the examples, ...
132 views

### Replace $z$ with interpolated function and plotting

I start off with this equation $z(x,y) = sin(xy)$. I create an interpolation from $0 < x < 5$ and $0 < y < 5$. I then use this interpolation on a simple function $w(x,y) = x + y + z(x,y)$ ...
312 views

### Issue in ParallelTable after evaluating another function using NDSolve and FindRoot. What is wrong with this inverse?

I am trying to find the inverse of a function which is defined through NDSolve and NIntegrate. The question is pretty similar ...
186 views

### Error message: Coordinate index 0 is out of range for the enclosing GraphicsComplex

I am unable understand following error message: Coordinate index 0 is out of range for the enclosing GraphicsComplex. How to fix it? Attached data here: pts and polygons. See also end of question. <...
313 views

### Create Table of replacement rules

I want to create a table of replacement rules. ...
78 views

### What's going wrong with this button! [duplicate]

I'm implementing an Adaline algorithm where all inputs are 1x5526 and the output is a number from 1 to 10. I have this two functions defined and worked outside the ...
587 views

### For-loop not working as I expect

I want to do this: When 10 <= t < 130, give t -> 1; When 130 <= t<300, give ...
663 views

### How can I plot a function that is the sum of another function?

I plotted m[t], but actually what I want to plot is g[t], which is a summation of m[t] from ...
204 views

### Why Min cannot be used as constrains of NMinimize?

I met a strange problem when trying to do an optimization. Initialization code, ...
98 views

This is Right. NestWhile[Log, 100, # > 1 &] {100} //. {x_} /; x > 1 :> {Log[x]} 100. //. x_ /; x > 1 :> Log[x] This is wrong,why? ...
289 views

### updating code from 5.0 to 9.0

I am updating a code from a 5.0 version to a 9.0 version. I am speaking about "Advanced visual quantum mechanics". There is a package with this code:  ...
345 views

### Weighted mean of complex exponential function using NIntegrate

I have defined the following functions: ...
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### What's the wrong when I use NestWhileList?

Problem : A Happy number is a number that if one squares its digits and add them together, and then take the result and square its digits and add them together again and keep doing this process, one ...
206 views

### Optimization of power tower fractal generator [closed]

I tried to optimize the code for generating power tower fractals from here. As the author suggested, I tried to memorize the points already tested in a list. Here is my code : ...
226 views

### What's wrong with my code for finding primes?

From here I found a fast method to make prime list, the python version works well, but my Mathematica version does not. Obviously ,169 is not a prime number. What's ...
143 views

### Reuse a dynamic list [duplicate]

Consider this Dynamic list ...