Linked Questions

44
votes
8answers
10k views

About multi-root search in Mathematica for transcendental equations

I have some questions for multiroot search for transcendental equations. Is there any clever solution to find all the roots for a transcendental equation in a specific range? Perhaps ...
21
votes
4answers
9k views

Find all roots of an interpolating function (solution to a differential equation)

I'm trying to find all the roots of the solution to a differential equation. Using NSolve or Reduce I don't get the roots, so I'm using an iterative method which I found in physicsforums.com. This ...
6
votes
4answers
1k views

Which root does FindRoot give?

I think that usually, FindRoot will give the root that's closest to the starting point. But see the example below, where I try to find the root of $\cos x=0$. If I ...
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 ...
1
vote
5answers
1k views

Finding roots of transcendental equation and collecting into a list

I am working on a physics reserach project for school and I have run into some troubles working Mathematica. I am a fairly inexperienced mathematica user so any help would very much be appreciated. I ...
4
votes
2answers
698 views

Roots of Whittaker W function

I am interested in finding the roots $u$ of the equation $$ W_{1,\imath b}(a)=0, $$ where $W_{\kappa,\mu}(z)$ denotes the Whittaker $W$ function, $a>0$ is a fixed parameter, $\imath=\sqrt{-1}$ and $...
2
votes
3answers
288 views

slwcon and eincr in integrating multivariate Gaussian random variables

Why is the following integration involving multivariate Gaussian distribution so slow and generating an error? Is there a better integration strategy? All that I'm doing is considering $(X_1,X_2,X_3,...
2
votes
1answer
807 views

FindRoot of interpolating function from NDSolve

I am having issues finding the root of an interpolating function obtained from NDSolve. For example: ...
1
vote
0answers
476 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
2answers
128 views

The coefficients with NIntegrate [duplicate]

I try to compute the coefficients b[i] , $i=2,...,m$. I got the following output: ...
3
votes
1answer
163 views

WorkingPrecision in a sum

If I am interested in getting a fairly precise plot of f2 below, can I use WorkingPrecision to do this? ...
3
votes
0answers
125 views

Incorrect roots from FindRoot [closed]

I am working on finding the permafrost active layer in a specific region and I have plotted depth vs temp. I need to find the root of the depth vs time for every time I have (over 9000 times) and <...
0
votes
0answers
117 views

Robust FindRoot search

I have the following simulation that models a rocket landing (flat Earth, no atmosphere, constant gravitational acceleration), which uses root finding to figure out when to start and stop the engines ...
2
votes
0answers
28 views

Indexing items in multiple lists to find a specific solution

Broadly, I am looking for a solution numerically using FindRoot, but the output seems to be be quite sensitive to the initial guesses for one variable in particular, so I am running the function over ...