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

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1answer
75 views

How to plot a solution set? [duplicate]

I have two functions, let's call them $F1$ and $F2$. Both take the same three arguments: $x1, x2$ and $\epsilon$. With every $\epsilon^* \in [0,1]$, there should be either zero or one unique point ...
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1answer
83 views

Solve the interpolating function

I would have asked how to obtain the x given the y in an interpolating function, and I found the answer from here. But another question raised. I was dealing with measurement of the spectral ...
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2answers
41 views

how do I find the unknown coefficients of coupled equations

How do I find the unknown constants $x, y, z$ interms of a and b, using Mathematica. \begin{equation} \begin{split} 1&=-x+y+z \\ ...
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1answer
36 views

Expanding in terms of a function in Solve

I am almost sure Mathematica has a way to do what I am looking for. I am trying to fit a quadratic T(x) = ax^2 + bx + c to three values of the function analytically. I proceed as follows: ...
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2answers
43 views

Using result of Solve as plot parameter

Recently I have faced a problem I would appreciate it, if you helped me I have the following code in Mathematica I want to plot a function let say z * 10 * t where ...
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1answer
61 views

Solve equation in a interval

I have a particle bouncing in a rigid box, my code is this: ...
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2answers
106 views

Solve implicit system of equations

Hello everybody I try to solve this system of functions and try to plot it: x == 0.5(1.+Tanh[0.5*(x*y^2-eps1)/t] y == Tanh[(x^2*y+eps2)/t] with eps1 = 0. and ...
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0answers
40 views

Impose conditions on differential equations

This is my first post in Mathematica Stack Exchange, so thanks for your help and sorry for any rookie mistakes. I am solving the Einstein equations for two vectorial pertubations h_Alpha and v_Alpha ...
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1answer
38 views

“MemoryAllocationFailure” in DSolve

Mathematica 10.4, Windows 10, 6 GB RAM, 64 bits When I trying to solve DSolve[{v'[t] == 100 - 0.15 v[t]^2, v[0] == 30}, v[t], t] I get ...
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3answers
203 views

Solving equation

How can I solve this equation: ((a^2 - 1)*((a^2 - 1)*ArcTanh[a] - a))/(2*Sqrt[2*(a^2 - 1)^4]) == C*x I am looking a solution for $a$ in function of $x$. I tried ...
2
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1answer
97 views

Maximize a variable in NSolve Function

I want to solve a set of trigometric coupled equations with the NSolve funcion while at the same time trying to maximize a variable which has to be real and between ...
3
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3answers
172 views

Cantor Pairing Function

I'm inspecting the Cantor pairing function, that we can find on this link here. But the strange thing is that Mathematica is outputting a wrong result to me. The code below shows the strange ...
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0answers
39 views

Using previous outputs and equations for 3d plots

I am extremely new to Mathematica, and am trying to obtain some plots for my research work. I need to find the roots of a polynomial, and using the roots individually, I need to obtain another ...
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0answers
43 views

Working of ForAll

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0answers
35 views
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0answers
42 views

Hash in Eigenvalue calculation [duplicate]

When I tried to find the eigenvalue of a 5x5 matrix, I get the following ...
2
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1answer
114 views

Differential Equation with Numerically Integrated Boundary Conditions

I have a second order differential equation that I'd like to solve numerically, and then integrate its solution twice to get the parametric equations of a curve. The ODE is: $2 ...
0
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0answers
91 views

Impose a boundary condition to a function

Background I am trying to impose a boundary condition on a function of two variables $u(x_1,x_2)$. The boundary condition is: $u(x_1,0)=A\cos(\omega x_1)$. The same function in mathematica ...
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0answers
43 views

Solve huge system of inequalities

I need to solve the huge system of algebraic linear inequalities (up to milions). But the built-in methods like Solve, Reduce, FindInstance... seems to be very slow. I have problem to solve "only" 100 ...
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4answers
339 views

Equation for the line of intersection between two planes

I have two equations: 2x + y + z = 1 3x - 2y - z = 5 And I have calculated the answers on paper, which gave me $x = 1 + t$, $y = -1 + 5t$ and $z = -7t$. So my ...
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0answers
33 views

Solvability of a system of equations and inequalities

I want to know if a given system of equalities and inequalities is solvable or not. I do not need the solution, rather just about its solvability. I tried a few variations, but I believe that it can ...
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2answers
93 views

Solving recursion relation from power series

I am interested in solving differential equations in the form of power series. Let's say we have following equation: $$f^{\prime \prime} (\rho) + \left( \frac{2 e^{-k \rho}}{\rho} - \varepsilon ...
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1answer
111 views
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1answer
74 views

norm squared of imaginary function with unknown constants

Is it possible to evaluate the norm squared and expand a given function similar to this, $$ ...
1
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2answers
55 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: ...
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1answer
38 views

Select positive solution based on value of parameter

I want to select positive solutions to Solve[], but as the sign of the solutions depend on the value of some parameters/other variable, I am not sure how to do ...
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1answer
61 views

Differential equation [closed]

How does one solve this differential equation? $$y' = \frac{x^3 + 2x^2 y - y^3}{x^3 + x^2 y}$$
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1answer
52 views

solve homogeneous linear system

Let x^2*y + x^2*z + x*y^2 + y^2*z + xz^2 + yz^2+ xyz =0 x^3-xyz + x^2*y-xyz + x^2*z-xyz + xy^2-xyz - xy*z+y^2*z - xyz+xz^2 - xyz+yz^2 =0 x^3+3*xyz+7*yz^2 + xy*z+y^3+9*y*z^2 + x^2*y+6*xyz+4*y*z^2 ...
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2answers
74 views

Solutions to Non-linear equation system

I have been trying to solve the following system of equations: ...
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1answer
56 views

System of polynomial equations with Solve does not converge

The Exp-method [1] is an analytical solution method for differential equations. Essentially, the method boils down to the solution of a system of nonlinear polynomial algebraic equations. In [1] (and ...
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0answers
33 views

Why differential equation reduces? [duplicate]

I am trying to ND-Solve the following equation: eqns = {x''[t] == -x[t], x'[0] == 0, x[0] == 4} The problem, is when I enter it, Mathematica reduces it to ...
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1answer
55 views

Precision in calculation [duplicate]

I am writing some code to demonstrate the effect of the number of significant figures a coefficient has on the solution of a nonlinear equation. I define the coefficient as follows: ...
0
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1answer
70 views

NDSolve for a system of nonlinear coupled pde

I try to solve a system($n$) of coupled nonlinear 1-d PDE's which is basically coupled sine-Gordon equations (through 2nd spatial derivative) in time and space. I am interested in the dynamics when I ...
0
votes
1answer
89 views

Find partial solution for underdetermined system of Boolean equations (Minesweeper)

In this article about creating a Minesweeper solver, the author talks about using matrices to solve given portions of a Minesweeper board. While reading that, I thought of a different way to limit the ...
1
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0answers
50 views

Estimating processing time for commands

I am trying to evaluate some equations by using Taylor series of expansion (Series[], ExpandAll[], and Normal[] command), and using n equation and n unknown (Solve). Following is not full command (if ...
0
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1answer
46 views

Symbolic Maximization: does not work with symbolic power?

Simple question from a beginner: I seem to be unable to do maximization if the variable has a power specified symbolically instead of numerically? ...
2
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1answer
47 views

Passing a list to a nested vector function

In order to apply a newton-rhapson algorithm to solve a set of nonlinear vector equations such as these, f[x_, y_] = {x^2 - 3*y + 6, (y + 1)^2 - x - 33} I need ...
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1answer
65 views

How can I solve a certain statics problem [closed]

Does someone have any idea how to solve it or from where to start?
0
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1answer
82 views

Solve non-linear system of 16 equations [closed]

I need a solution to a non-linear system of 16 equations, I am trying the following command and nothing is happening: ...
3
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3answers
166 views

Determine integer results using Solve

I'm trying to solve a Pythagorean pairs for m and n (for m and n < 100) which give integer p values in the following equation: Sqrt[m^2 + n^2] == p I may ...
0
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1answer
117 views

NSolve takes too long time!

I am trying to solve the following problem numerically and I faced two things: 1- It takes too long time to give solutions. 2- there are many roots for the equation but NSolve doesn't give all thee ...
4
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1answer
72 views

SystemException[“MemoryAllocationFailure”] Uncaught SystemException returned to top level from NSolve

Bug introduced in 10.0.0 When trying to solve 8 equations in 8 unknowns, I get SystemException["MemoryAllocationFailure"]. I am not sure if I am doing something ...
1
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1answer
92 views

Different interpretation of system of equations

Given the variables ...
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2answers
52 views

Solving simple transcendental equation [duplicate]

I would like to solve Tan[x] == 1/x Solve[] does not work, suggesting that there is no nice analytical solution for x. Surprisingly, NSolve[] does not work ...
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1answer
63 views

Is this expression solvable and if so is there a better way to do it?

I would like to solve this polynomial of third order for its roots: ...
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0answers
33 views

Solving an inequality with Root objects

Given q1 = Root[(48 a^2 + 16 b) #^4 - (40 a^3 + 168 a b)#^3 + (-45 a^4 + 225 a^2 b + 72 b^2) #^2 + (27a^3 b - 162 a b^2) # + 27 b^3 &,1] Now, I know that the ...
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2answers
63 views

Mathematica shows complex roots while asked for reals?

I ran the following code in Mathematica ToRadicals[Reduce[-14848 c^4 + 38016 c^3 x - 30888 c^2 x^2 + 6480 c x^3 + 1215 x^4 == 0 && c < 0,x,Reals]] ...
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0answers
32 views

Different root objects

Consider the quartic polynomial $$(48a^2+16b)x^4-(40a^3+168 ab)x^3+(-45 a^4+225a^2 b+ 72b^2)x^2+(27a^3 b - 162 ab^2)x+27b^3, \qquad (*)$$ where $a<0$. Consider ...