Linked Questions

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 ...
3
votes
2answers
200 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, $$\...
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 ...
9
votes
5answers
401 views

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, ...
5
votes
3answers
674 views

How can I solve this equation: $(47^{(u + 1)} + 3^{(u + 1)})/(u + 1) ==50^{1.5}/1.5$?

Solve[(47^(u + 1) + 3^(u + 1))/(u + 1) ==(50^1.5)/1.5,u] The code I tried is above, but it showed me a message problem "Solve was unable to solve the system ...
13
votes
6answers
723 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 ...
5
votes
3answers
790 views

Why does the following Solve take so long?

Why does the following take Mathematica so long to reply to? Solve[BetaRegularized[0.5, k, n - k - 1] == 0.035, k] where $n = 1000$ By the way, In case there is ...
2
votes
1answer
154 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 ...
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? ...
2
votes
2answers
553 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 ...
1
vote
2answers
575 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: ...
1
vote
0answers
493 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 ...
9
votes
3answers
587 views

Labeling solutions of an Eigenvalue equation involving Bessel functions

I'm solving the Schrödinger equation for a particle in an annular geometry with hard wall boundary conditions and I've reduced it to the following equation: $$J_m(k\,R_1)\,Y_m(k\,R_2) - J_m(k\,R_2)\,...
0
votes
0answers
147 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: ...
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.

15 30 50 per page