Linked Questions

6
votes
2answers
480 views

Techniques to find all local minima of black box function with n continuous derivatives?

I have a blackbox function f on [a,b] that is known to be continuous, and has n continuous derivatives. The function uses polynomial interpolations (but isn't a polynomial interpolation itself), so no ...
5
votes
2answers
7k views

Find all roots in range

Is there any way to check for all roots in a range? Jens' findAllRoots function is pretty good, but runs at approx. 10% of roots missed when I ran a quick check on ...
3
votes
2answers
198 views

Eigen values of a third order linear homogenous ODE

From a system of PDEs where i used the following ansatz: $$\theta_w(x,y) = e^{-\beta_h x} f(x) e^{-\beta_c y} g(y)$$. $F(x) := \int f(x) \, \mathrm{d}x$ and $G(y) := \int g(y) \, \mathrm{d}y$ So, $$\...
2
votes
2answers
550 views

Difficulty finding roots of an interpolation function from NDSolve

I have been trying to find the point at which one of the solutions of a system of two ODEs crosses zero. I used the method suggested in this answer to a previous question, which seemed to be the most ...
2
votes
2answers
773 views

How do I get all the roots within a certain range for an equation? [duplicate]

I wish to find ALL the roots of the following equation $ x \tan(ax) - c = 0$ within a range, where a and c are constants I control. I've been using ...
2
votes
2answers
2k views

Find roots of a function involving Bessel functions

I'm trying to find the roots of a function involving Bessel functions. Here is my code ...
1
vote
2answers
54 views

Finding positive region of continous function

I want to find (and plot) the positive region (within a certain domain say x<3,y<3) of a function ...
1
vote
2answers
573 views

Finding roots of a function that includes Bessel functions [duplicate]

I'm fairly new to Mathematica so forgive any stupid mistakes. Here's my function: ...
4
votes
1answer
113 views

Creating a For Loop for a equation that has many solutions [duplicate]

I have two equations like these. I want to create a for loop that gives to me all intersection points of the two equations. How can I do that? ...
3
votes
1answer
519 views

Finding all zeroes - mysterious missing roots

Finding all the roots of a function of one real variable has been discussed extensively in e.g. Find all roots of an interpolating function (solution to a differential equation) (answer no. 2 by Jens ...
2
votes
1answer
153 views

Complex roots of the determinant of symbolic matrix

I am trying to find multiple complex and real roots of the determinant of symbolic matrix. Someone advised me to use Muller's method. I am wondering if there is a package already written to do this ...
0
votes
1answer
73 views

Help me solve this equation; I believe this is a transcendental equation [duplicate]

please can someone help me solve (x*L)+B*tan(x*L)=0, solve for x when B=10;L=0.1. The equation looks innocent but I need to find 1st 5 roots of equ.
1
vote
0answers
52 views

How to find x for certain y from InterpolatingFunction [duplicate]

As shown in the picture, I get the data after using NDSolve. Now I want to get the x for cetain y, how can I do this? The last three lines is the way I try to ...
1
vote
0answers
488 views

Obtaining values from interpolating functions

A similar question has been asked in the post HERE but the current question is more complicated: I have the following differential system ...
0
votes
0answers
146 views

Probleme with Ted Ersek's RootSearch package [duplicate]

The following question is a logical continuation of this one. The Ted Ersek's RootSearch package doesn't work with this code: ...

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