The Stack Overflow podcast is back! Listen to an interview with our new CEO.

All Questions

Filter by
Sorted by
Tagged with
2
votes
1answer
70 views

A question regarding 3D plot

Updated I have an equation: $x (z \ln z) = y$. For different values of $x$ and $y$ we can solve this equation for z, for example, for $x = 3$ and $y =1$, we have: ...
0
votes
1answer
59 views

How to substitute by NDSolve solution to plot a new function

Assume I got some function by NDSolve , like y(t) ...
1
vote
0answers
55 views

how to solve nonlinear differential equations which calls other functions that uses states and time as input while solving NDSolve?

I have nonlinear differential equations which require output from other functions and those functions require time and some states as input. I'm writing the Mathematica code bellow the equation. $p=...
0
votes
1answer
39 views

How to create a correct density plot from “NDSolve” solution?

I would like to create the projection of a solution in plane from the differential equation set solution. However, the way I did it is not as I would like it, it does not have a smoothness. Here's ...
0
votes
1answer
20 views

Properly defining and plotting a function that requires `NSolve`

I want to defined a function that solves some equation numerically: ...
0
votes
1answer
82 views

How to solve set of linear differential equation in Mathematica?

I have a set of linear differential equations and are written in this format [X']=[Y]-[R] where [P][Y]=[Q] My actual P matrix size is of 20x20 and Q is of 20x1 and Y is of 20x1. I have written this ...
1
vote
1answer
103 views

Shooting Method for Numerical Solution

I am trying to solve the following nonlinear differential equation using the shooting method. The equation is a boundary value problem with boundary condition x[0]=Pi and x[Infinity]=0. In order to ...
10
votes
2answers
307 views

Solving Cahn-Hilliard equation: LinearSolve: Linear equation encountered that has no solution

I have built the Cahn-Hilliard Eqs. in MMA (Mixed Formulation, second order), However, it doesnot work in MMA using Finite Element. LinearSolve: Linear equation encountered that has no solution. And ...
0
votes
0answers
35 views

Why do all the Roots not show up in ContourPlot of an equation?

Roots by Normal Method: f[x_] := (Sin[x] + Cos[x] - Sqrt[2]) Sqrt[-11 x - x^2 - 30]; Reduce[(Sin[x] + Cos[x] - Sqrt[2]) Sqrt[-11 x - x^2 - 30] == 0, x] Which ...
5
votes
1answer
135 views

Runtime too long for NDSolveValue, FindRoot breaks down at sharp turns

I have two equations: $$ \frac{2}{3}\thinspace\left(\frac{\varepsilon}{\Delta}\right)^{\frac{3}{2}}=\sum_{i=1,2} \sigma_i\lambda_{i}\left(1+\lambda_{i}^{2}\right)^{\frac{1}{4}}E\left(\frac{\pi}{2},k_{...
0
votes
1answer
66 views

Problems with manipulation

I am plotting geodesics on an ellipsoid. My problem is that I cannot do the manipulation, from a, b, c. From the starting point and the initial vector, the manipulation works well, but from the ...
1
vote
1answer
66 views

ListPlot3D of the results of FindRoot

I have a system of 2 simultaneous equations where i want to calculate the values of Tc and Tc which ranging with the values of two variables which are wfc and V. I tried to evaluate it by using ...
1
vote
2answers
131 views

Solving BPV of second order nonlinear ODE through NDSolve

I'm trying to solve a 2nd order related ODE system in two region using Piecewise. BC: 1) y'[0]=0 and at y'[1.6]=0 while at 1 <...
0
votes
1answer
36 views

How do I plot the output of Solve as a function? [closed]

I have a system of equations (13 eq) and I want to solve for S. There are four solutions in terms of k and ...
3
votes
1answer
67 views

Help with solving a PDE and plotting its solution

I have trouble with solving the PDE with periodic boundary condition, which appears to be stiff somewhere, so I tried "StiffnessSwitching". But the code still doesn'...
0
votes
1answer
32 views

Plotting roots of a non polynomial function

I'd like to plot the solutions of a function f(y)=k, when f(y) is non polynomial. This is the Mathematica script I have produced so far: ...
0
votes
0answers
48 views

Problem with a plot

I have a function which has a dependency on x alone. I wanted to find the roots of this equation, so I tried plotting the equation, but I am getting the error "integer expected at position 2 in Surd[0....
2
votes
1answer
188 views

Solving a system of PDEs on a piecewise polynomial domain

I wish to solve following system of equations with Dirchlet and Neumann boundary conditions on an piecewise polynomial (cubic spline) shaped domain as showed here. ...
0
votes
1answer
59 views

Plotting a transcendental equation [duplicate]

I would like to get this graphic: from this article. Here $\kappa$ and $\varepsilon_{dd}$ are related by: ...
0
votes
0answers
63 views

find gravity acceleration (g) using FindFit

I need some help again, with this simple exercise: Use the data to determine g, but this time use the functional form T = 2 pi Sqrt[L/g] for the period T of a ...
0
votes
0answers
41 views

Why do I get a blank graph when using Manipulate with NDSolve?

I'm trying to model an SIR model using the Manipulate function so that I can change the parameters. Although, when I enter in the following code: ...
2
votes
1answer
45 views

Find x at a given t and f(x,t) == constant from a system of coupled PDE

Is it possible to find the speed of a moving front (produced by the below code) in which modulating beta changes the speed of the front? Basically, I am trying to map the x-values of f(x,t)=0.5 ...
3
votes
1answer
122 views

Finding the maximum real part of roots

Suppose that I have this problem ...
1
vote
2answers
65 views

Verification of plotted points of intersection and curve orthogonality

A unit circle and tractrix (with differential equations respectively), $$ \cos \phi =y;\, \sin \phi= y $$ and tangent slope $$\phi = \theta +\pi/2 $$ are plotted to verify orthogonality. Due ...
2
votes
2answers
132 views

Solving 2D Reaction-Diffusion with Explicit Euler Method

I am trying to solve this following 2D-Diffusion equation (I wrote it in Word, so it looks nice) (Note: I am solving this for a 100x100 mesh point) I tried to solve the above equation using the ...
0
votes
1answer
55 views

How to Plot between square of the solution and square of the term occurring in the equation?

I am trying to plot between (mod[E01])^2 and (mod[as])^2 and for that using the following code as seen below. But not getting any plot. If anyone knows this, is welcome. ...
0
votes
4answers
164 views

How can I solve this transcendental equation in Mathematica?

I want to solve the following equation $\frac{Sin[a[x]]}{a[x]}$ - x = 0, for x in range {0,1}. I tried the FindRoot method but it gives only one root. I want to find the roots for this equation for ...
2
votes
1answer
181 views

Solving an equation with constraints

This is a question that follows up from this post: Select one among multiple solutions that satisfies a certain condition and 3D Plot it with varying simulation values I was trying to apply the ...
1
vote
1answer
198 views

To solve self consistent equations by simultaneously plotting them

How can we solve a pair of equations that have to be solved self-consistently (even by plotting them simultaneously) . ...
0
votes
1answer
55 views

Why is my code not giving me a graph? (finite difference method) [closed]

For a finite difference method code, I after altered it a bit for my needs. I am no longer getting errors, however I am not getting my graph to show. ...
-1
votes
1answer
80 views

Liquefying of Nitrogen & Oxygen Gaseous to Liquid Phase. Thermodynamics. How to plot solution? Solved [closed]

Process of Liquefying of air composed of 79% Nitrogen & 21% Oxygen from Gaseous to Liquid Phases as Follows: 1) When Temperature is higher than T>83 k they both are gas. 2) at T=83 k and less ...
1
vote
1answer
100 views

Finding all positive roots of a transcendental equation [duplicate]

I need to find all positive roots of the following transcendental equation 2*cot(x) = 6.4*x-0.1563/x I know that the roots can be visualised as the intersecting ...
2
votes
1answer
51 views

Plotting numerical solutions (multi solutions)

I am trying to plot the solutions of this equation. ...
2
votes
3answers
71 views

Plotting Solve output automatically

I am trying to solve a characteristic polynomial and plotting its output. The problem is that I do not know how to take the output automatically. My current code is ...
1
vote
2answers
46 views

How to Plot solve function

So I have Emin[T_, d_] := If[T == 0, 0, 1/(-1 + E^(1/T)) - d/(-1 + E^(d/T))]; which I can solve wonderfully for ...
-3
votes
1answer
105 views

How can i plot graph and its root?

I am using this code. wn = 100; aap = 0.2; ome = 9; Solve[{(2 x + 2) ((dco - wn aap x)^2 + 1) + 4*ome*x == 0}, {x}] Plot[{x /. %}, {dco, -40, 0}] I am using ...
1
vote
2answers
50 views

Finding a solution to an equation and plotting it

I have this equation that I want solve explicitly so that $\omega$ is dependent of $k$ like this $\omega (k)$ and then plot it on a plane for k, but I have no idea which function to use. This is the ...
0
votes
1answer
83 views

Solving system of equations for coordinates

This is my first time here, so let me know if there's something I need to add to the post etc. Anyway, I need some help with Mathematica and linear algebra, and I got some tips that this would be the ...
2
votes
1answer
219 views

Finding all roots to equation [duplicate]

I'm currently doing some Mathematica exercises, and I'm stuck on this one task where you're supposed to plot the functions h(t)= |3-t^2|+|t-1|-t^2 , g(t)=3sin(t) in the same grap, and then find all ...
2
votes
4answers
165 views

How to generate repetitive graphs?

I need to create several graph for different values of a parameter $h$. The code is the following ...
4
votes
1answer
321 views

Solving the eigenvalue problem for a double well potential using a 1D particle in a box as a basis set

My first question is how would I go about getting the 1D particle in a box eigenfunctions using matrix techniques and how would I use the particle in a box eigenfunctions as a basis set for the ...
0
votes
1answer
60 views

How to introduce a NSolve into a ContourPlot?

I have an equation that I want to solve, and I'm using DensityPlot, as I was told here NSolve two unknowns $ r, x $ in order to have a curve $ r(x) $ . Meaning I have a relation $f(r,x)=0$, and with ...
1
vote
2answers
77 views

Storing values of NDSolve or NIntegrate

I am looking in plotting some solutions of NDSolve or NIntegrate but they take too much time to run, thus it is not handy if I ...
2
votes
2answers
84 views

Plotting solution to Differential Equation with separable variables [closed]

Got this differential equation $$y'=\frac{-x^2(y+1)}{y^2(x-1)}$$ If I try directly to DSolve it ...
0
votes
1answer
47 views

Plot[] fails to show all results of Solve[]

I'm interested in the intersection points of two functions: $y=r+x$, where $r$ is the constant, and $y=ln(1+x)$. The following code plots the two intersection points for different (negative values) of ...
0
votes
1answer
67 views

Finding the root of a Transcendental equation [closed]

I'm trying to find R in the transcendental equation. $R + u_r\,t=(\frac{a_1\,B}{\nu}\, \gamma_0^2)^{\frac{3}{4}} \sigma R \,e^{\frac{3 \sigma}{v_{sh}\,t_{acc}}(R-R^*)}$ Everything except R is a ...
0
votes
1answer
41 views

Plotting a=f(b) and b=g(a) on the (a,b) plane when neither has a closed solution

I've searched for a solution but haven't found one yet, but this is possibly an easy fix - I'm new to Mathematica. I have two functions, each with $(a,b)$ as arguments and both with no closed form ...
1
vote
1answer
56 views

Performing a FindRoot from Numerical integration

I am trying to evaluate: FindRoot[Xfnew[γ, w, Hi, mx]*92*10^23*γ^(4/(1 + w)) == 1198/10000, {Hi, hs}, MaxIterations -> 10000] for some starting value hs,...
-1
votes
1answer
192 views

Solve equation: Exponent is out of bounds for function PolynomialGCD

I am trying to solve the equation below but it returns this error :Exponent is out of bounds for function PolynomialGCD". I would be gratuful if you someone help to solve this equation. ...
2
votes
2answers
58 views

How to plot Implicit function Exp^(-ArcTan[y/x]) * Sqrt[x^2 + y^2]==C , for example, C -> Range[-12, 12]?

I tried many functions to plot implicit function: Exp[-ArcTan[y/x]] * Sqrt[x^2 + y^2]==C Does anyone have an idea how to do that ? (This is General Integral of ...