Questions on the analytic and numeric equation solving functions of Mathematica (Solve, Reduce, NSolve, FindRoot, DSolve, RSolve, etc.).

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0answers
16 views

How to solve an equation with previously set variables

I am trying to set up an equation with multiple variables and use the Solve function to simplify it and plot the result. However, when I plug in my equation to the Solve function, it just gives me an ...
4
votes
0answers
30 views

Make NSolve faster by keeping only one solution

Dear Mathematica users, NSolve usually returns all numerical solution it can find. When a variable is squared in some equation, ...
2
votes
1answer
68 views

How to solve time dependent pde?

I have set out to try and solve a time dependent wave equation with specific boundary conditions, but I am running into a bit of a snag. As you can see, I am trying to solve for the wave function u[t, ...
0
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0answers
62 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 ...
0
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1answer
87 views

Solving and Plotting Infinite sums over solutions to transcendental equation involving Bessel functions

I am trying to use Mathematica to plot the following equation $E(q,\Delta)$ vs $qa$, for set values of $ D \Delta/a^2$ and $\bar\rho a/D$. I have looked at other stackexchange posts which deal with ...
3
votes
4answers
321 views

How to solve an equation with a nested function

I have the equation f[f[x]] == 28 + 9 x How can I solve this for f[x]? I note that this post relates to the topic, but ...
0
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1answer
117 views

Solve returns empty list

I want to solve these equations but Mathematica gives no answer. ...
-1
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0answers
26 views

Please check my code for gauss elimination and rectify the mistake [on hold]

clc; clear all; prompt = 'Enter No of Unknowns \n' ; m = input(prompt) ; a = zeros(m,m) ; x = 0 ; for x = 1:m for y = 1:m prompt = 'Enter element(x,y) \n' ; ...
0
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0answers
32 views

Solving Inequality with Exponentiation and Log [on hold]

I have an inequality that I am not able to proove which is $Log[d] <\frac{(-1 + d^M) (d^M - d^N) N} {d^{M}(-1 + d^N) M (M - N)}$ with $0<\delta<1$, $M\geqq1$, $N>M$ and thus $N>1$. I ...
0
votes
1answer
40 views

NSolve/Reduce Help: 3Equations/5Variables

I have this system of equations that I have been trying to solve using Mathematica; I had been running this last evaluation for 30 hours and my computer crashed :/! So, instead of deciding to run ...
0
votes
1answer
44 views

Probems using 2 For and a AppendTo to cycle through my Equation to solve some matrixes

I am trying to solve a few problems here. I have an equation with multiple variables that I am trying to solve in For loop method. I will attach the file below. In addition I am trying to get it to ...
1
vote
1answer
59 views

Expectation of Largest Roots of Bernoulli distributed coefficient Monomials

I am interested in determining the most probable maximum values of the real roots of polynomials of form $P(x)=\sum_{k=0}^n a_{k} x^k$ where the degree $n$ will have a defined value (say 3,4,5...) and ...
1
vote
2answers
85 views

how do I control the output of Reduce function?

Reduce[x*y > 50 && x*y < 100 && x < 100 && x > 1 && y > 1 && y < 50, {x, y}, Integers] what if I want ...
0
votes
1answer
59 views

Solving a polynomial where variables are constrained to take only some values

I want to find out which combinations of 1's and 0's would make this kind of equation be null: ...
0
votes
1answer
87 views

How to solve algebra equations containing integration and parameters?

I'm trying to solve two nonlinear algebra equations for two unknown parameters, U and Tf. Since some terms in these equations contain integration, and the integration also contains U and Tf. The main ...
1
vote
1answer
69 views

How can I solve my system of simultaneous polynomial equations?

I want to solve the system of equations (y + 1)(a - x^p*y^q) == 0 (y + 1)x^p*y^q - c*y == 0 But I am getting the massage this system can't be solved by ...
0
votes
0answers
33 views

Why Mathematica does not Maximize when using parameter

I have recently started using Mathematica and I have got a question using it. I would appreciate if one could help me figuring out how to handle it. I have the following simple maximisation code <...
3
votes
5answers
166 views

Intersection coordinates of two spheres

I am trying to obtain a list of coordinates at which two spheres intersect. Take for example the spheres: sp1=Sphere[{0, 0, 0}, 1] and ...
6
votes
2answers
213 views

Solve a system of M equations without specifying M [on hold]

I am trying to write my game-theoretic model in Wolfram Language. There is only one remaining step and I am not sure if it is within reach of Wolfram Language (or Mathematica). I describe a simplified ...
5
votes
3answers
1k views

How can I solve the equation with integers as a solution?

I want to solve the equation $$(x-1)^2 + (y-1)^2 + (z-1)^2 = 49$$ where $x$, $y$, $z$ are integer and $x \neq 1$, $y \neq 1$, $x \neq 1$. How do I tell Mathematica to do that?
1
vote
1answer
47 views

solve equation with integer maximum [closed]

how to solve with Mathematica a)$ \left [\kern-0.10em\left[ 5 x \right]\kern-0.15em\right] = 2x+1$ b) $ \left [\kern-0.10em\left[1/ 5 x \right]\kern-0.15em\right] > 2x+1$ EDIT = double ...
3
votes
2answers
88 views

solving PDE equation like Helmholtz equation in 2D

In my project I need to solve following equation analytically could anyone help me ? As I read the other questions, my equation seems like Helmholtz equation $$ \triangledown^2 u(x,y) - k_cu(x,...
0
votes
1answer
932 views

Solve non linear system of equations

I am trying to solve a system of two equations with two unknowns. In these equations I have, a part from constants: Unknown nr 1, $$D_{\perp}$$ Unknown nr 2, $$\omega_C$$ Known function of r: $$\mu(...
2
votes
3answers
180 views

Truncate an infinite continued fraction at order 2000

I want to solve an equation which contains an infinite continued fraction $F(n)$. Then I must (obviously) truncate this continued fraction at $n=2000$. The problem here is that Mathematica does not ...
11
votes
1answer
318 views

How to solve for the intersection points of two ellipses?

I have a parametric equation of two ellipses as follow $\begin{cases} x=a_1 \text{sin$\theta $}+b_1 \text{cos$\theta $}+c_1 \\ y=d_1 \text{sin$\theta $}+e_1 \text{cos$\theta $}+f_1 \\ \end{cases}...
0
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0answers
40 views

Solving linear system with non-commuting coeffcients

Is there a way to solve a linear system of equations where the coefficients do not commute? (Warning: my two-days of looking so far suggest this may be an unsolved math problem, but I figured I could ...
4
votes
2answers
249 views

Why Can't `DSolve` Find a Solution for this ODE?

I wanted to find a basis for the set of solutions of the following ODE. $$y^{''}+\frac{1}{x^2+1}y^{'}(x)+\left[-1-\frac{1}{x^2+1}\right]y(x)=0$$ But when I try to use ...
1
vote
1answer
83 views

Matrix equations solving

can you explain me the easiest way for solving this matrix equation? I have this matrix: a={{-4,1,3,0},{-2,7,1,-1},{1,-1,9,-3},{-1,0,5,-10} and the Equation is: ...
5
votes
3answers
230 views

How to get the coordinates of the intersection of two lines from a ListLinePlot?

Suppose I have two curves intersect at some point, how can I read the coordinates from the graph, not read by eye, but find it with more precision by computer. For example, here are two lists created ...
3
votes
1answer
71 views

Generating plane equation from LinearSolve

I will ask a simple question and might have an issue on the site that explains better about it, but not found. I am formulating a code that defines me an equation that I can generate a plot. ...
1
vote
1answer
71 views

getting a following error,large data points,desired output-best fit to expt. data sets

I am trying to carry out list operation but running into a following error I have large data sets(more than 0.2 million data points) and desired output will be a best fit (numerical data points ) to ...
1
vote
1answer
41 views

Splitting Logical Expression in list of expressions

I have long results of a Reduce statement in the form of {(expr1) || (expr2) || (expr3) || ...} I am looking for a way to split ...
0
votes
1answer
83 views

Solving a System of Simultaneous Equations [duplicate]

I have the command: Solve[{Cos[η] == Sqrt[3/6], Sin[α] Cos[η] == Sqrt [1/6], Sin[α] Sin[η] == Sqrt [2/6]}, {η, α}] I get the output ...
1
vote
0answers
51 views

NSolve and FindRoot failing to evaluate

So I am integrating a Piecewise function and then using NSolve to find out where the limits of integration lie to satisfy an ...
2
votes
1answer
66 views

Finding input of the function $f(a,b,c) = (d,e)$ such that $|d-e|$ = constant for $d\in[d_0,d_1]$

The actual question contains a few more parameters than mentioned in the title, but the idea will remain very similar. Lets begin abstractly; I have a certain function $f(a,b,c) = (d,e,g,h)$. I am ...
0
votes
1answer
53 views

Find the minimum of several functions

I have 6 functions of four variables $ f_i: \mathbb{R}^4 \rightarrow \mathbb{R},\, i \in 1..6$ For each function $f_j$ I want to find the subset of $ \mathbb{R}^4 $, called $S_j$, for which it is ...
26
votes
5answers
28k views

Assign the results from a Solve to variable(s)

I understand Mathematica can't assign the results of a Solve to the unknowns because there may be more than 1 solution. How can I assign the 4 values of following result to variables?
0
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0answers
62 views

solving a set of 10 non-linear system of equations

I have a system of equations and I want to solve it to get a1, a2, b1, ...
0
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0answers
31 views

Making function that returns output of FindRoot [duplicate]

I'm trying to make a function that returns the solution to an equation which involves three variables, where the input variables for the function are the other two variables. So far, it runs, but ...
2
votes
2answers
255 views

Incorrect numerical derivative of function that uses FindRoot

I am trying to plot the derivative of function g[x] below where g[x] is defined as the root of another equation. However, I am ...
1
vote
2answers
154 views

After NumberForm I cannot apply a Sine function. Why?

After NumberForm I cannot apply a Sine function. Why? This works: sol1 = x /. Solve[x^2 - 3 == 0, x] Sin[sol1] Output = $\{-Sin[\sqrt{3}],Sin[\sqrt{3}]\}$ Also ...
0
votes
1answer
77 views

Module output rules like Solve FindRoot etc built-in functions

How do I print rules {x -> values} as an output from my module? I'd like it formatted just like those from the built-in functions, so that users can use Out[ ] or % to directly apply the rules. ...
3
votes
1answer
231 views

How to change parameters to equations of physical properties they belong to in an equation?

First off, I want to apologize for my poor English as I am not a native speaker. In my physics research, I had to solve a system of equations, from which I would get a solution for the speed of an ...
0
votes
0answers
89 views

Help numerically solve this non-linear PDE with singularity

I have trouble finding a numerical solution to the partial differential equation below. It seems to be a singularity in the solution somewhere, so I searched online and found that it is suggested to ...
3
votes
2answers
69 views

Using Solve[ ] inside a Module

I want to use Solve[] inside a Module. If I make the variables solved for local to the module, they are treated differently than ...
0
votes
1answer
154 views

Given $y$, find the $x$ value of a point on a Bezier curve

I have linear equation of Bezier curve with one control point: f[x_] := (1 – t)^2 x0 + 2 (1 – t) t x1 + t^2 x2; f[y_] := (1 – t)^2 y0 + 2 (1 – t) t y1 + t^2 y2; ...
0
votes
2answers
37 views

Solve inside of InputField is not dynamic

On the 7th line, I have an InputField that I want to dynamically change as I change the input. It solves an equation that is later used to determine the change in y intercept in the graph. However, ...
1
vote
1answer
49 views

Using solution of an equation [duplicate]

I want to solve something like f(x)=0 and then have the real solution be set as the value of another variable. I can't figure out how to do it. I tried something like this as an example, but it didn't ...
5
votes
1answer
264 views

Finding an analytic solution of a cubic equation

I have been trying to solve a cubic equation $$y=zy^3 + z$$ in $y$ – that is, my desired result is a function $y(z)$ satisfying the equation. Now, there are three solutions of this equation and ...