# Tagged Questions

Questions on the numerical functions of Mathematica, implementing numerical methods and numerical computing with Mathematica.

0answers
30 views

### Help needed for solving nonlinear ODEs [on hold]

I want to solve fourth order nonlinear ODE with known boundary conditions using Predictor Corrector methods, or shooting methods in Mathematica but don't know how to solve them with these techniques. ...
3answers
73 views

### How can I use the command Minimize of this trigonometric function? [duplicate]

I want to find the minimum of the function $\sin^6 x + \cos^6 x$. I tried Minimize[{Sin[x]^6 + Cos[x]^6, 0 <= x <= 2 Pi}, x] I got {Cos[2 ArcTan[1 - ...
2answers
639 views

### Function to subdivide interval into n evenly-spaced points

[This post needs better tags than I could come up with. Edits to the tags would be particularly welcome.] I realize that it is trivial to define a function that takes an interval (i.e. two ...
2answers
155 views

### Help Please : Error in plotting the solutions of FindRoot

I want to find the roots of an equation using FindRoot as a function of a real parameter K and then plot the real and imaginary solutions vs. the parameter K. The function I'm trying to find the ...
1answer
30 views

### How shortening argument test when declaring functions?

When defining some functions which depend in many arguments sometimes we need to include question Q constraints to diminish processing time. My question is simple, there is a way to shorten a long ...
2answers
246 views

### Water Hammer - Numerically solving system of PDEs

I'm trying to use Mathematica to solve the water hammer effect. ...
2answers
227 views

### BitShiftRight produces incorrect results in Version 10

fixed in 10.0.2 With Mathematica 10 for Mac, BitShiftRight works properly on lists of up to 100000 numbers, but appears to give incorrect results when threaded ...
2answers
102 views

### Increasing number of decimal places with FixedPoint

I've tried: In[169]:= newton3[x_] := N[1/2 (x + 3/x)]; FixedPointList[newton3, 1.0] Out[170]= {1., 2., 1.75, 1.73214, 1.73205, 1.73205, 1.73205} Of course: ...
1answer
706 views

### Fast Spherical Harmonics radiative transfer

This is a rather specific question and I apologize for spamming you with some lengthy code. But it could be interesting for some reader and maybe you can help out, so please bear with me. I am using ...
2answers
58 views

### Iteration of NDSolve

I have a problem with iteration of the result of NDSolve. Namely, the following code works fine ...
1answer
90 views

1answer
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### Why Abs[Infinity] is an element of the real numbers

Element[Abs[Infinity], Complexes] returns False, that's right. But ...
0answers
47 views

### Handling Accuracy and Simplifying

I have the following problem. I have a system of non-linear equations that I log-linearize around a certain point, let's call it point A, using a function that I ...
3answers
66 views

### High-Precision NSolve

I need to calculate the intersection of two curves f1[x_] := ((Zl ρ ) Exp[-x]) f2[x_] := (α k e^2 /x^2) Where ...
0answers
34 views

### How to make a real number parameter go 2 decimal precision? [duplicate]

I'm new at community and I'm starting with Mathematica. I'm now having a trouble with a very simple problem which for many of you might be really obvious. In documentation ...
1answer
61 views

### How to speed up Min of DateObjects?

I'm in version 10.0.1 using a Dataset to do some plots and things. For one of the plots I need to get the minimum date of a some filtered set of the ...
2answers
2k views

### How to discretize a nonlinear PDE fast?

I wish to numerically solve the following PDE. Although there are some complete discussions for solving PDEs in tutorial/NDSolvePDE, there is no hint for the nonlinear case by discretization. Thus, I ...
0answers
108 views

### NMinimize ignores constraints

I have a problem with NMinimize - I try to minimize quite a complicated function and use a couple of constraints (the way it is shown in the documentation). Now, ...
1answer
80 views

### How to find all roots of a complex number [duplicate]

Finding all roots, and I know there are four f them, of this (1 - i)^(1/4) Not only real, but imaginary as well
4answers
132 views

### RegionMember with some tolerance?

Can I specify some tolerance for the new geometric-computation function? RegionMember[Line[{{0, 0}, {1, 0}}], {.5, 0}] (* True *) While: ...
1answer
39 views

### Error messages from NIntegrate [closed]

I've been trying to work on some integrals (Actuarial Science, for those interested) but somehow this always returns an error for me. ...
2answers
112 views

### Display All Output Numbers in HEX

How might I modify Mathematica such that I can get the following functionality when working with HEX values. The odd lines are input and the even output. Red values should be the HEX values. ...
0answers
48 views

### Number recognition in Mathematica [closed]

Suppose that I have a number $n$ with many decimal digits of precision. What is the code to use to get Mathematica to recognize possible closed-form expressions for that number?
1answer
157 views

### Why does taking advantage of Listable change the results of a numerical computation slightly?

I have two variables: t0, and teta0. The first is computed using several nested sums, the second is computed taking advantage to ...
2answers
157 views

### How to define even permutations correctly?

I define even permutations as following, but there may be some error. I use it in two different way and get different output. ...
3answers
2k views

### Identifying critical points/lines of 2/3D image/cubes

Upshot I am interested in identifying critical points of a 3D field/cubes (maxima, minima, tube-like and wall-like saddle points) and 2D field/image (maxima, minima, saddle points). I.e. the ...
0answers
46 views