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### 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 ...
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### 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 ...
24k views

### How to find all the local minima/maxima in a range

I want to find : all local maxima in range all local minima in range From those points I can interpolate and combine functions upper and lower boundary. What I am really interested in, is the mean ...
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### How to find numerically all roots of a function in a given range?

It is common that I search numerically for all zeros (roots) of a function in a given range. I have written two simple minded functions that perform this task, and I know of similar functions on this ...
784 views

### Solving this challenging ODE

Consider the ODE: $$w^{(4)}(x) + (L-x)w''(x) - w'(x) = 0$$ with some of the following boundary conditions: free: $w'' = 0$, $w'''=0$, clamped: $w = 0$, $w'=0$, pivot: $w = 0$, $w''=0$. Two such ...
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### NDEigenvalues vs. FindRoot for finding the eigenvalues of Airy equation?

Say I am trying to find the first 5 eigenvalues of the differential equation $f''(x)=\lambda x f(x)$, on the interval [-1,0], with boundary conditions $f(-1)=f(0)=0$. I will try to do this 3 ways, ...
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### 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: ...
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### 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 ...
86 views

### Selecting data from a list

Let's create a simple data list Clear["Global`*"]; data = Table[{i, Sin[i]}, {i, 0, 6 \[Pi], 0.01}]; L0 = ListPlot[data] Now I want to find for which values of \$...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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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### 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? ...
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### 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.